SUMMARY

This summary highlights selected information from this joint proxy statement/prospectus. It may not contain all of the information that is important to you. You are urged to read carefully the entire joint proxy statement/prospectus and the other documents referred to or incorporated by reference into this joint proxy statement/prospectus in order to fully understand the merger agreement and the proposed merger. See “Where You Can Find More Information” beginning on page [—] of this joint proxy statement/prospectus. Each item in this summary refers to the page of this joint proxy statement/prospectus on which that subject is discussed in more detail.

The Companies (See Page [—])

Comcast Corporation

Comcast is a global media and technology company with two primary businesses, Comcast Cable and NBCUniversal Media, LLC, which is referred to in this joint proxy statement/prospectus as NBCUniversal. Comcast was incorporated under the laws of Pennsylvania in 2001 and, through its predecessors, has developed, managed and operated cable systems since 1963. In 2011, Comcast closed the NBCUniversal transaction in which it acquired control of the businesses of NBCUniversal, and in 2013, Comcast acquired the remaining 49% common equity interest in NBCUniversal that it did not already own. Comcast presents its operations for Comcast Cable in one reportable business segment, which is referred to in this joint proxy statement/prospectus as Cable Communications, and its operations for NBCUniversal in four reportable business segments.

The Cable Networks, Broadcast Television, Filmed Entertainment and Theme Parks segments comprise the NBCUniversal businesses.

In 2013, Comcast’s Cable Communications segment generated 65% of Comcast’s consolidated revenue and 80% of its operating income before depreciation and amortization.

Comcast’s other business interests primarily include Comcast-Spectacor, which owns the Philadelphia Flyers and the Wells Fargo Center arena in Philadelphia and operates arena management-related businesses.

The principal trading market for shares of Comcast Class A common stock (NASDAQ: CMCSA) and shares of Comcast Class A Special common stock (NASDAQ: CMCSK) is NASDAQ. There is no established public trading market for shares of Comcast Class B common stock. The principal executive offices of Comcast are located at One Comcast Center, Philadelphia, Pennsylvania 19103-2838; its telephone number is (215) 286-1700; and its website is www.comcastcorporation.com.

This joint proxy statement/prospectus incorporates important business and financial information about Comcast from other documents that are not included in or delivered with this joint proxy statement/prospectus. For a list of the documents that are incorporated by reference, see “Where You Can Find More Information” beginning on page [—] of this joint proxy statement/prospectus.

Time Warner Cable Inc.

TWC is among the largest providers of video, high-speed data and voice services in the U.S., with technologically advanced, well-clustered cable systems located mainly in five geographic areas—New York State (including New York City), the Carolinas, the Midwest (including Ohio, Kentucky and Wisconsin), Southern California (including Los Angeles) and Texas. TWC’s mission is to connect its customers to the world—simply, reliably and with superior service. As of December 31, 2013, TWC served approximately 14.4 million residential customers and 624,000 business customers who subscribed to one or more of its video, high-speed data and voice services. TWC’s business services also include networking and transport services (including cell tower backhaul services) and enterprise-class, cloud-enabled hosting, managed applications and services. TWC also sells video and online advertising inventory to a variety of local, regional and national customers.

TWC was incorporated as a Delaware corporation on March 21, 2003, and TWC and its predecessors have been in the cable business for over 40 years in various legal forms. The principal trading market for TWC common stock (NYSE: TWC) is the New York Stock Exchange. TWC’s principal executive offices are located at 60 Columbus Circle, New York, New York 10023; its telephone number is (212) 364-8200; and its website is www.twc.com.

This joint proxy statement/prospectus incorporates important business and financial information about TWC from other documents that are not included in or delivered with this joint proxy statement/prospectus. For a list of the documents that are incorporated by reference, see “Where You Can Find More Information” beginning on page [—] of this joint proxy statement/prospectus.

Tango Acquisition Sub, Inc.

Merger Sub was incorporated in the State of Delaware on February 11, 2014, and is a wholly owned subsidiary of Comcast. Merger Sub was formed solely for the purpose of completing a merger with TWC. Merger Sub has not carried on any activities to date, except for activities incidental to its formation and activities undertaken in connection with the merger.

The principal executive offices of Merger Sub are located at One Comcast Center, Philadelphia, Pennsylvania 19103-2838; and its telephone number is (215) 286-1700.

The Merger (See Page [—])

Comcast, Merger Sub and TWC have entered into the merger agreement. Subject to the terms and conditions of the merger agreement and in accordance with applicable law, Merger Sub will be merged with and into TWC, with TWC continuing as the surviving corporation. Upon completion of the merger, TWC will be a wholly owned subsidiary of Comcast, and TWC common stock will be delisted from the New York Stock Exchange and deregistered under the Securities Exchange Act of 1934, as amended, which is referred to in this joint proxy statement/prospectus as the Exchange Act.

A copy of the merger agreement is attached as Annex A to this joint proxy statement/prospectus. You should read the merger agreement carefully because it is the legal document that governs the merger.

Special Meeting of Stockholders of TWC (See Page [—])

Meeting. The TWC special meeting will be held on [—], 2014, at [—], located at [—], at [—], local time. At the TWC special meeting, TWC stockholders will be asked to consider and vote on the following proposals:

Record Date. The TWC board of directors has fixed the close of business on [—], 2014, as the record date for determination of the stockholders entitled to vote at the TWC special meeting or any adjournment or postponement of the TWC special meeting. Only TWC stockholders of record at the record date are entitled to receive notice of, and to vote at, the TWC special meeting or any adjournment or postponement of the TWC special meeting. As of the close of business on [—], 2014, there were [—] shares of TWC common stock outstanding. Each holder of TWC common stock is entitled to one vote for each share of TWC common stock owned at the record date.

Quorum. The presence at the TWC special meeting, in person or by proxy, of the holders of a majority of the votes entitled to be cast for each proposal at the record date (the close of business on [—], 2014) will constitute a quorum for such proposal. Abstentions will be deemed present at the TWC special meeting for the purpose of determining the presence of a quorum. Shares of TWC common stock held in “street name” with respect to which the beneficial owner fails to give voting instructions to the broker, bank, nominee or other holder of record will not be deemed present at the TWC special meeting for the purpose of determining the presence of a quorum. There must be a quorum for business to be conducted at the TWC special meeting. Failure of a quorum to be represented at the TWC special meeting will necessitate an adjournment or postponement and will subject TWC to additional expense.

Adjournment. In accordance with TWC’s by-laws, the TWC special meeting may be adjourned by the Chairman of the meeting. If the TWC special meeting is adjourned, stockholders who have already submitted their proxies will be able to revoke them at any time prior to their use.

Required Vote. To adopt the merger agreement, the affirmative vote of holders of a majority of the outstanding shares of TWC common stock entitled to vote is required. TWC cannot complete the merger unless its stockholders adopt the merger agreement. Because adoption requires the affirmative vote of holders of a majority of the outstanding shares of TWC common stock entitled to vote, a TWC stockholder’s abstention from voting, the failure of a TWC stockholder who holds his or her shares in “street name” through a broker, bank, nominee or other holder of record to give voting instructions to that broker, bank, nominee or other holder of record or a TWC stockholder’s other failure to vote will have the same effect as a vote “AGAINST” the adoption of the merger agreement.

To approve, on an advisory (non-binding) basis, “golden parachute” compensation payments that will or may be paid by TWC to its named executive officers in connection with the merger, the affirmative vote of a majority of the votes cast at the TWC special meeting by holders of shares of TWC common stock is required. An abstention is not considered a vote cast. Accordingly, assuming a quorum is present, a TWC stockholder’s abstention from voting, the failure of a TWC stockholder who holds his or her shares in “street name” through a broker, bank, nominee or other holder of record to give voting instructions to that broker, bank, nominee or other holder of record or a TWC stockholder’s other failure to vote will have no effect on the outcome of any vote to approve the “golden parachute” compensation proposal.

Stock Ownership of and Voting by TWC Directors and Executive Officers. At the record date for the TWC special meeting (the close of business on [—], 2014), TWC’s directors and executive officers and their affiliates

beneficially owned and had the right to vote [—] shares of TWC common stock at the TWC special meeting, which represents approximately [—]% of the shares of TWC common stock entitled to vote at the TWC special meeting.

It is expected that TWC’s directors and executive officers will vote their shares “FOR” the adoption of the merger agreement and “FOR” the “golden parachute” compensation proposal, although none of them has entered into any agreement requiring them to do so.

Special Meeting of Shareholders of Comcast (See Page [—])

Meeting. The Comcast special meeting will be held on [—], 2014, at [—], located at [—], at [—], local time. At the Comcast special meeting, Comcast shareholders will be asked to consider and vote on the following proposals:

Record Date. The Comcast board of directors has fixed the close of business on [—], 2014, as the record date for determination of the shareholders entitled to vote at the Comcast special meeting or any adjournment or postponement thereof. Only Comcast Class A shareholders and Comcast Class B shareholders who held shares at the record date are entitled to receive notice of, and to vote at, the Comcast special meeting or any adjournment or postponement of the Comcast special meeting. Holders of shares of Comcast Class A Special common stock are not entitled to vote at the Comcast special meeting. As of the close of business on [—], 2014, there were [—] shares of Comcast Class A common stock outstanding and 9,444,375 shares of Comcast Class B common stock outstanding. For all matters to be voted on by Comcast Class A shareholders and Comcast Class B shareholders as a single class, Comcast Class B common stock has a nondilutable 33 ¹⁄₃% of the combined voting power of Comcast Class A common stock and Comcast Class B common stock. The number of votes per share to which a Comcast Class A shareholder is entitled is determined based on a formula set forth in Comcast’s articles, which gives effect to the nondilutable voting power of the Comcast Class B common stock at any time. As of the record date, (i) each Comcast Class A shareholder is entitled to [—] votes for each share of Comcast Class A common stock owned by such shareholder and (ii) each Comcast Class B shareholder is entitled to 15 votes per share for each share of Comcast Class B common stock owned by such shareholder.

Quorum. The presence at the Comcast special meeting, in person or by proxy, of the holders of a majority of votes entitled to be cast for each proposal at the record date (the close of business on [—], 2014) will constitute a quorum for such proposal. Abstentions will be deemed present for the purpose of determining the presence of a quorum. Shares of Comcast common stock held in “street name” with respect to which the beneficial owner fails to give voting instructions to the broker, bank, nominee or other holder of record will not be deemed present for the purpose of determining the presence of a quorum. There must be a quorum for the proposal to approve the stock issuance to be voted on at the Comcast special meeting. Failure of a quorum will necessitate an adjournment or postponement of the Comcast special meeting and will subject Comcast to additional expense. If the Comcast special meeting is adjourned for one or more periods aggregating at least 15 days due to the absence of a quorum, Comcast shareholders who are entitled to vote and who attend (including by proxy) the adjourned meeting, even though they do not constitute a quorum as described above, will constitute a quorum for the purpose of acting on the stock issuance.

Required Vote. To approve the stock issuance, the affirmative vote of a majority of the votes cast at the Comcast special meeting by Comcast Class A shareholders and Comcast Class B shareholders, voting together as a single class, is required. Comcast cannot complete the merger unless its shareholders approve the stock

issuance. An abstention is not considered a vote cast. Accordingly, assuming a quorum is present, a Comcast shareholder’s abstention from voting, the failure of a Comcast shareholder who holds his or her shares in “street name” through a broker, bank, nominee or other holder of record to give voting instructions to that broker, bank, nominee or other holder of record or a Comcast shareholder’s other failure to vote will have no effect on the outcome of any vote to approve the stock issuance.

The separate Class B vote is also required to approve the stock issuance. Following entry into the merger agreement, pursuant to the voting agreement, holders of all the outstanding shares of Comcast Class B common stock delivered the written consent, which is sufficient to approve the stock issuance for purposes of the separate Class B vote.

To approve the adjournment of the Comcast special meeting if necessary to solicit additional proxies if there are not sufficient votes to approve the stock issuance at the time of the Comcast special meeting, whether or not a quorum is present, the affirmative vote of a majority of the votes cast at the Comcast special meeting by Comcast Class A shareholders and Comcast Class B shareholders, voting together as a single class, is required. An abstention is not considered a vote cast. Accordingly, a Comcast shareholder’s abstention from voting, the failure of a Comcast shareholder who holds his or her shares in “street name” through a broker, bank, nominee or other holder of record to give voting instructions to that broker, bank, nominee or other holder of record or a Comcast shareholder’s other failure to vote will have no effect on the outcome of any vote to adjourn the Comcast special meeting.

Stock Ownership of and Voting by Comcast Directors and Executive Officers. At the record date for the Comcast special meeting (the close of business on [—], 2014), Comcast’s directors and executive officers and their affiliates beneficially owned and had the right to vote [—] shares of Comcast Class A common stock at the Comcast special meeting, which represents approximately [—]% of the shares of Comcast Class A common stock entitled to vote at the Comcast special meeting, and beneficially owned and had the right to vote 9,444,375 shares of Comcast Class B common stock at the Comcast special meeting, which represents 100% of the shares of Comcast Class B common stock entitled to vote at the Comcast special meeting.

Brian L. Roberts, Chairman and Chief Executive Officer of Comcast, and certain of his family trusts and investment vehicles, have entered into the voting agreement described below, pursuant to which they have agreed to vote all of their shares in favor of the stock issuance. It is expected that the other Comcast directors and executive officers will vote their shares “FOR” the stock issuance and “FOR” the adjournment of the Comcast special meeting if necessary to solicit additional proxies if there are not sufficient votes to approve the stock issuance at the time of the Comcast special meeting, although none of these other Comcast directors and executive officers has entered into any agreement requiring them to do so.

The Voting Agreement (See Page [—])

Concurrently with the execution of the merger agreement, TWC entered into a voting agreement with Brian L. Roberts, BRCC Holdings LLC, Irrevocable Deed of Trust of Brian L. Roberts for Children and Other Issue dated June 10, 1998 and Irrevocable Deed of Trust of Ralph J. Roberts for Brian L. Roberts and Other Beneficiaries dated May 11, 1993.

Following entry into the merger agreement and pursuant to the voting agreement, these Comcast shareholders delivered the written consent, which is sufficient to approve the stock issuance for purposes of the separate Class B vote. The written consent will automatically be revoked upon a termination of the voting agreement.

In addition, the Comcast shareholders who are parties to the voting agreement have agreed to vote all of their shares of Comcast Class A common stock and Comcast Class B common stock (i) in favor of the stock

issuance for purposes of the single class vote, (ii) in favor of any proposal to adjourn any meeting of Comcast shareholders to solicit additional proxies if there are not sufficient votes for the approval of the stock issuance and (iii) against any corporate action that would frustrate the purposes or impede the consummation of the merger. The voting agreement imposes certain restrictions on these Comcast shareholders’ right to transfer shares of Comcast Class B common stock, as described under “The Voting Agreement,” beginning on page [—] of this joint proxy statement/prospectus. The voting agreement will terminate upon the earliest to occur of: (i) the completion of the merger, (ii) the date of termination of the merger agreement in accordance with its terms, and (iii) the date of any amendment, modification, supplement or waiver to any provision of the merger agreement that has not been consented to by Brian L. Roberts or holders of a majority of the outstanding shares of Comcast Class B common stock and that would increase the 2.875 exchange ratio, change the form of merger consideration or amend provisions of the merger agreement relating to regulatory matters in a manner materially adverse to investors. If the voting agreement is terminated prior to the completion of the merger, the written consent will be revoked. The voting agreement provides that no provisions contained therein limit the discretion of Brian L. Roberts to take or not take any action in his fiduciary capacity as an officer or director of Comcast.

As of February 12, 2014, the Comcast shareholders who are parties to the voting agreement held in the aggregate 471,435.749 shares of Comcast Class A common stock (representing approximately 0.02% of the outstanding shares of Comcast Class A common stock) and 9,444,375 shares of Comcast Class B common stock (representing 100% of the outstanding shares of Comcast Class B common stock). As of the record date for the Comcast special meeting, the Comcast shareholders who are parties to the voting agreement held in the aggregate [—] shares of Comcast Class A common stock (representing [—]% of the outstanding shares of Comcast Class A common stock) and 9,444,375 shares of Comcast Class B common stock (representing 100% of the outstanding shares of Comcast Class B common stock), which together represent approximately [33.35]% of the combined voting power of Comcast Class A common stock and Comcast Class B common stock. Based on [—] outstanding shares of Comcast Class A common stock and 9,444,375 outstanding shares of Comcast Class B common stock on the record date for the Comcast special meeting, and after taking into account the expected votes of the directors and executive officers of Comcast and the Comcast shareholders who are parties to the voting agreement, approval of the proposal for the stock issuance will require the affirmative vote of the holders of an additional [—] outstanding shares of Comcast Class A common stock at the Comcast special meeting (representing approximately [—]% of the outstanding shares of Comcast Class A common stock that are not owned by the directors and executive officers of Comcast or the Comcast shareholders who are parties to the voting agreement).

A copy of the voting agreement is attached as Annex B to this joint proxy statement/prospectus.

What TWC Stockholders Will Receive in the Merger (See Page [—])

If the merger is completed, TWC stockholders will be entitled to receive, in exchange for each share of TWC common stock that they own immediately prior to the merger, 2.875 shares of Comcast Class A common stock, and cash payable in lieu of any fractional shares as described below.

Comcast will not issue any fractional shares in the merger. Instead, the total number of shares of Comcast Class A common stock that each TWC stockholder will receive in the merger will be rounded down to the nearest whole number, and each TWC stockholder will receive cash, without interest, for any fractional share of Comcast Class A common stock that he or she would otherwise receive in the merger. The amount of cash for fractional shares will be calculated by multiplying the fraction of a share of Comcast Class A common stock that the TWC stockholder would otherwise be entitled to receive in the merger by the Comcast closing price.

Example: If you own 100 shares of TWC common stock at the time the merger is completed, you will be entitled to receive 287 shares of Comcast Class A common stock. In addition, you will be entitled to receive an amount of cash equal to 0.5 of a share of Comcast Class A common stock multiplied by the Comcast closing price.

The ratio of 2.875 shares of Comcast Class A common stock for each share of TWC common stock, which is referred to in this joint proxy statement/prospectus as the exchange ratio, is fixed, which means that it will not change between now and the date of the merger, regardless of whether the market price of shares of either Comcast Class A common stock or TWC common stock changes. Therefore, the value of the merger consideration will depend on the market price of shares of Comcast Class A common stock at the time TWC stockholders receive shares of Comcast Class A common stock in the merger. Based on the closing price of a share of Comcast Class A common stock on NASDAQ on February 12, 2014, the last trading day before the public announcement of the merger agreement, the merger consideration represented approximately $158.82 in value for each share of TWC common stock. Based on the closing price of a share of Comcast Class A common stock on NASDAQ on [—], 2014, the most recent practicable trading day prior to the date of this joint proxy statement/prospectus, the merger consideration represented approximately $[—] in value for each share of TWC common stock. The market price of shares of Comcast Class A common stock has fluctuated since the date of the announcement of the merger agreement and will continue to fluctuate from the date of this joint proxy statement/prospectus to the date of the TWC special meeting and the date the merger is completed and thereafter. The market price of shares of Comcast Class A common stock when received by TWC stockholders upon completion of the merger could be greater than, less than or the same as the market price of shares of Comcast Class A common stock on the date of this joint proxy statement/prospectus or at the time of the TWC special meeting.

No Dissenters’ or Appraisal Rights (See Page [—])

Neither TWC stockholders nor Comcast shareholders have dissenters’ or appraisal rights with respect to the merger.

Treatment of TWC Equity Awards (See Page [—])

At completion of the merger, each option to purchase shares of TWC common stock (whether or not exercisable or vested) and each restricted stock unit that is settleable in shares of TWC common stock (whether or not vested) that is outstanding immediately prior to completion of the merger and held by a then-current employee of TWC will be converted into an option or restricted stock unit, as applicable, with respect to Comcast Class A common stock, after giving effect to the exchange ratio. In the case of options, the aggregate option exercise price of each TWC option will be divided by the exchange ratio to determine the exercise price of each new award. Such converted options and restricted stock units will otherwise be subject to the same terms and conditions as were applicable immediately prior to completion of the merger.

However, in the case of (i) any restricted stock units (which will include deferred stock units held by non-employee directors) held by current or former non-employee directors of TWC or former employees of TWC (in each case, whether or not vested); and (ii) any options (whether or not exercisable or vested) held by former employees of TWC, such options or restricted stock units will be cancelled, and TWC will pay the holder cash, less applicable withholding taxes, at or promptly following the merger. All options held by a former employee of TWC that have a per share exercise price (as adjusted to give effect to the exchange ratio) equal to or exceeding the Comcast closing price will be immediately cancelled without any right to consideration.

For options, the cash amount will be computed by first determining the number of shares of Comcast Class A common stock to which such former employee would be entitled if his or her options were converted into options as described in the paragraph above, and multiplying such number by the excess of (i) the Comcast closing price over (ii) the adjusted exercise price per share of such option (also determined in accordance with the above paragraph).

For restricted stock units, the cash amount will be determined by multiplying (x) the number of shares of TWC common stock subject to such unit immediately prior to completion of the merger by (y) 2.875, with any fractional shares rounded down to the next lower whole number of shares of Comcast Class A common stock, and then multiplying the product of (x) and (y) by the Comcast closing price.

Recommendations of the TWC Board of Directors (See Page [—])

After consideration and consultation with its advisors, the TWC board of directors unanimously determined that the merger agreement, the merger and the other transactions contemplated by the merger agreement are fair to and in the best interests of TWC’s stockholders and unanimously approved and declared advisable the merger agreement, the merger and the other transactions contemplated by the merger agreement. The TWC board of directors unanimously recommends that TWC stockholders vote “FOR” the adoption of the merger agreement. For the factors considered by the TWC board of directors in reaching this decision, see “TWC Proposal I: Adoption of the Merger Agreement and Comcast Proposal I: Approval of the Stock Issuance—TWC’s Reasons for the Merger; Recommendation of the Merger by the TWC Board of Directors” beginning on page [—] of this joint proxy statement/prospectus.

In addition, the TWC board of directors unanimously recommends that TWC stockholders vote “FOR” the “golden parachute” compensation proposal. See “TWC Proposal II: Advisory Vote On Golden Parachute Compensation” beginning on page [—] of this joint proxy statement/prospectus.

Recommendations of the Comcast Board of Directors (See Page [—])

After consideration and consultation with its advisors, the members of the Comcast board of directors present at the Comcast board meeting unanimously determined that the merger agreement, the merger, the stock issuance and the other transactions contemplated by the merger agreement are fair to and in the best interests of Comcast and unanimously approved and declared advisable the merger agreement, the merger, the stock issuance and the other transactions contemplated by the merger agreement. The Comcast board of directors unanimously recommends that Comcast shareholders vote “FOR” the stock issuance. For the factors considered by the Comcast board of directors in reaching this decision, see “TWC Proposal I: Adoption of the Merger Agreement and Comcast Proposal I: Approval of the Stock Issuance—Comcast’s Reasons for the Merger; Recommendation of the Comcast Board of Directors” beginning on page [—] of this joint proxy statement/prospectus.

The Comcast board of directors unanimously recommends that Comcast shareholders vote “FOR” the adjournment of the Comcast special meeting if necessary to solicit additional proxies if there are not sufficient votes to approve the stock issuance at the time of the Comcast special meeting. See “Comcast Proposal II: Adjournment of the Comcast Special Meeting” beginning on page [—] of this joint proxy statement/prospectus.

Opinions of TWC’s Financial Advisors (See Page [—])

Opinion of Allen & Company LLC

TWC has engaged Allen & Company LLC, which is referred to in this joint proxy statement/prospectus as Allen & Company, as a financial advisor in connection with the proposed merger. In connection with this engagement, TWC requested that Allen & Company evaluate and render an opinion to the TWC board of directors regarding the fairness, from a financial point of view, to holders of TWC common stock of the exchange ratio provided for in the merger. On February 12, 2014, at a meeting of the TWC board of directors held to evaluate the merger, Allen & Company rendered to the TWC board of directors an oral opinion, which was confirmed by delivery of a written opinion dated February 12, 2014, to the effect that, as of that date and based on and subject to the matters described in its opinion, the exchange ratio provided for in the merger was fair, from a financial point of view, to holders of TWC common stock.

The full text of Allen & Company’s written opinion, dated February 12, 2014, which describes the assumptions made, procedures followed, matters considered and limitations on the review undertaken, is attached to this joint proxy statement/prospectus as Annex C. Allen & Company’s opinion was intended for the benefit and use of the TWC board of directors (in its capacity as such) in connection with its evaluation of the exchange ratio provided for in the merger from a financial point of view and did not address any other term, aspect or implication of the merger. Allen & Company’s opinion did not constitute a recommendation as to the course of action that the TWC board of directors or TWC should pursue in connection with the merger, or otherwise address the merits of the underlying decision by TWC to engage in the merger, including in comparison to other strategies or transactions that might be available to TWC or in which TWC might engage. Allen & Company’s opinion does not constitute advice or a recommendation to any stockholder as to how such stockholder should vote or act on any matter relating to the merger or otherwise.

Opinion of Citigroup Global Markets Inc.

TWC also has retained Citigroup Global Markets Inc., which is referred to in this joint proxy statement/prospectus as Citi, as a financial advisor in connection with the proposed merger. In connection with this engagement, TWC requested that Citi evaluate the fairness, from a financial point of view, of the exchange ratio provided for in the merger to holders of TWC common stock. On February 12, 2014, at a meeting of the TWC board of directors held to evaluate the merger, Citi delivered to the TWC board of directors an oral opinion, confirmed by delivery of a written opinion dated February 12, 2014, to the effect that, as of that date and based on and subject to various assumptions, matters considered and limitations and qualifications described in its opinion, the exchange ratio provided for in the merger was fair, from a financial point of view, to holders of TWC common stock.

The full text of Citi’s written opinion, dated February 12, 2014, which describes the assumptions made, procedures followed, matters considered and limitations on the review undertaken, is attached as Annex D to this joint proxy statement/prospectus and is incorporated herein by reference. The description of Citi’s opinion set forth below is qualified in its entirety by reference to the full text of Citi’s opinion. Citi’s opinion was provided for the information of the TWC board of directors (in its capacity as such) in connection with its evaluation of the exchange ratio provided for in the merger from a financial point of view and did not address any other terms, aspects or implications of the merger. Citi was not requested to consider, and its opinion did not address, the underlying business decision of TWC to effect the merger, the relative merits of the merger as compared to any alternative business strategies or opportunities that might exist for TWC or the effect of any other transaction in which TWC might engage. Citi’s opinion is not intended to be and does not constitute a recommendation as to how any stockholder should vote or act on any matters relating to the proposed merger or otherwise.

Opinion of Morgan Stanley & Co. LLC

TWC also has retained Morgan Stanley & Co. LLC, which is referred to in this joint proxy statement/prospectus as Morgan Stanley, as a financial advisor in connection with the proposed merger. As part of that engagement, TWC requested that Morgan Stanley evaluate the fairness, from a financial point of view, to holders of TWC common stock of the exchange ratio pursuant to the merger agreement. On February 12, 2014, at a meeting of the TWC board of directors held to evaluate the merger, Morgan Stanley rendered its oral opinion, confirmed by delivery of a written opinion dated February 12, 2014, to the TWC board of directors to the effect that, as of that date and based on and subject to the procedures followed, assumptions made, matters considered and qualifications and limitations on the review undertaken by Morgan Stanley as set forth in its opinion, the exchange ratio pursuant to the merger agreement was fair, from a financial point of view, to holders of TWC common stock.

The full text of Morgan Stanley’s written opinion, dated February 12, 2014, which sets forth, among other things, the procedures followed, assumptions made, matters considered and qualifications and limitations on the review undertaken by Morgan Stanley in connection with its opinion, is attached as Annex E to, and is incorporated by reference into, this joint proxy statement/prospectus. This summary is qualified in its entirety by reference to the full text of such opinion. Morgan Stanley’s opinion was directed to the TWC board of directors and addressed only the fairness from a financial point of view to holders of TWC common stock of the exchange ratio provided for pursuant to the merger agreement as of the date of the opinion and did not address any other term or aspect of the merger agreement or merger. Morgan Stanley’s opinion did not address TWC’s underlying business decision to proceed with or effect the merger, or the relative merits of the merger as compared to any other alternative business transaction, or other alternatives, or whether or not such alternatives could be achieved or were available. Morgan Stanley expressed no opinion or recommendation as to how the stockholders of TWC or Comcast should vote at the stockholders’ meetings to be held in connection with the merger or otherwise.

Opinion of Financial Advisor to the TWC Independent Directors (See Page [—])

Opinion of Centerview Partners LLC

Centerview Partners LLC, which is referred to in this joint proxy statement/prospectus as Centerview, was retained as financial advisor to the independent members of the TWC board of directors, who are referred to in this joint proxy statement/prospectus as the TWC independent directors, in connection with the proposed merger. In connection with this engagement, Centerview was requested to evaluate the fairness, from a financial point of view, of the exchange ratio provided for pursuant to the merger agreement to holders of TWC common stock. On February 12, 2014, at a meeting of the TWC board of directors held to evaluate the merger, Centerview delivered to the TWC board of directors an oral opinion, confirmed by delivery of a written opinion dated February 12, 2014, to the effect that, as of that date and based on and subject to various assumptions, matters considered and limitations and qualifications described in its opinion, the exchange ratio provided for pursuant to the merger agreement was fair, from a financial point of view, to holders of TWC common stock (other than shares held by TWC as treasury stock or owned by Comcast prior to the effective time of the merger, which are referred to in this joint proxy statement/prospectus as excluded shares).

The full text of Centerview’s written opinion, dated February 12, 2014, which describes the assumptions made, procedures followed, matters considered and limitations on the review undertaken, is attached as Annex F and is incorporated herein by reference. The description of Centerview’s opinion set forth below is qualified in its entirety by reference to the full text of Centerview’s opinion. Centerview’s opinion was provided for the information and assistance of the TWC board of directors (in their capacity as directors and not in any other capacity) in connection with and for purposes of its evaluation of the exchange ratio provided for pursuant to the merger agreement from a financial point of view and did not address any other term or aspect of the merger agreement or the merger. Centerview expressed no view as to, and its opinion did not address, TWC’s underlying business decision to proceed with or effect the merger, or the relative merits of the merger as compared to any alternative business strategies or transactions that might be available to TWC or in which TWC might engage. Centerview’s opinion does not constitute a recommendation to any stockholder of TWC or any other person as to how such stockholder or other person should vote with respect to the merger or otherwise act with respect to the merger or any other matter.

Opinion of Comcast’s Financial Advisor (See Page [—])

Opinion of J.P. Morgan Securities LLC

On February 12, 2014, at the meeting of the Comcast board of directors at which the proposed merger was approved, J.P. Morgan Securities LLC, which is referred to in this joint proxy statement/prospectus as

J.P. Morgan, Comcast’s financial advisor in connection with the proposed merger, rendered to the Comcast board of directors an oral opinion, confirmed by delivery of a written opinion dated February 12, 2014, to the effect that, as of such date and based upon and subject to the factors, assumptions, qualifications and any limitations set forth in its written opinion, the exchange ratio in the proposed merger was fair, from a financial point of view, to Comcast.

The full text of J.P. Morgan’s written opinion, dated February 12, 2014, is attached as Annex G to this joint proxy statement/prospectus and is incorporated herein by reference. The full text of the opinion contains a discussion of, among other things, the assumptions made, matters considered, and qualifications and any limitations on the opinion and the review undertaken by J.P. Morgan in connection with rendering its opinion. Comcast shareholders are urged to read the opinion carefully and in its entirety. J.P. Morgan’s written opinion was addressed to the Comcast board of directors (in its capacity as such) in connection with and for the purposes of its evaluation of the proposed merger, was directed only to the fairness, from a financial point of view, to Comcast of the exchange ratio in the proposed merger and did not address any other aspect of the merger. J.P. Morgan expressed no opinion as to the fairness of the exchange ratio to the holders of any class of securities, creditors or other constituencies of Comcast or as to the underlying decision by Comcast to engage in the proposed merger. The opinion does not constitute a recommendation to any shareholder of Comcast as to how such shareholder should vote with respect to the proposed merger or any other matter.

For further information, see “TWC Proposal I: Adoption of the Merger Agreement and Comcast Proposal I: Approval of the Stock Issuance—Opinion of Comcast’s Financial Advisor” beginning on page [—] of this joint proxy statement/prospectus.

Ownership of Shares of Comcast Class A Common Stock After the Merger (See Page [—])

Based on the number of shares of TWC common stock and TWC options and restricted stock units outstanding as of [—], 2014, Comcast expects to issue approximately [—] shares of Comcast Class A common stock to TWC stockholders pursuant to the merger and reserve for issuance approximately [—] additional shares of Comcast Class A common stock in connection with the conversion, exercise or settlement of outstanding TWC options and restricted stock units. The actual number of shares of Comcast Class A common stock to be issued and reserved for issuance pursuant to the merger will be determined at completion of the merger based on the exchange ratio and the number of shares of TWC common stock and TWC options and restricted stock units outstanding at that time. Based on the number of shares of TWC common stock outstanding as of [—], 2014, and the number of shares of Comcast Class A common stock outstanding as of [—], 2014, it is expected that, immediately after completion of the merger, former TWC stockholders will own approximately [—]% of the outstanding shares of Comcast common stock (including Comcast Class A common stock, Comcast Class A Special common stock and Comcast Class B common stock), representing [—]% of the outstanding shares of Comcast Class A common stock and [—]% of the combined voting power of Comcast Class A common stock and Comcast Class B common stock.

Interests of Directors and Executive Officers of TWC in the Merger (See Page [—])

When considering the recommendation of the TWC board of directors that TWC stockholders vote in favor of the adoption of the merger agreement and the recommendation of the Comcast board of directors that the Comcast shareholders approve the stock issuance, TWC stockholders and Comcast shareholders should be aware that directors and executive officers of TWC have certain interests in the merger that may be different from or in addition to the interests of TWC stockholders and Comcast shareholders generally. The TWC board of directors and the Comcast board of directors were aware of these interests and considered them, among other things, in evaluating and negotiating the merger agreement and the merger and in recommending that TWC stockholders adopt the merger agreement and Comcast shareholders approve the stock issuance.

These interests include the following:

These interests are described in further detail under “Interests of Certain Persons in the Merger—Interests of Directors and Executive Officers of TWC in the Merger” and “The Merger Agreement—Indemnification and Insurance” beginning on pages [—] and [—], respectively, of this joint proxy statement/prospectus.

Listing of Shares of Comcast Class A Common Stock and Delisting and Deregistration of TWC Common Stock (See Page [—])

Comcast will apply for listing on NASDAQ, where shares of Comcast Class A common stock are currently traded, of the shares of Comcast Class A common stock to be issued in the merger. If the merger is completed, the shares of Comcast Class A common stock to be issued in the merger will be listed on NASDAQ, and TWC shares will no longer be listed on the New York Stock Exchange and will be deregistered under the Exchange Act.

Completion of the Merger Is Subject to Certain Conditions (See Page [—])

As more fully described in this joint proxy statement/prospectus and in the merger agreement, the obligation of each of Comcast and Merger Sub, on the one hand, and TWC, on the other hand, to complete the merger is subject to the satisfaction or waiver of a number of conditions, including the following:

Comcast and TWC cannot be certain when, or if, the conditions to the merger will be satisfied or waived, or that the merger will be completed.

The Merger May Not Be Completed Without All Required Regulatory Approvals (See Page [—])

Completion of the merger is conditioned upon the receipt of certain governmental clearances or approvals, including, but not limited to, the expiration or termination of the waiting period relating to the merger under the HSR Act, approval of the FCC and certain other governmental consents and approvals from state regulators and franchise authorities.

Under the HSR Act, certain transactions, including the merger, may not be completed unless certain waiting period requirements have expired or been terminated. The HSR Act provides that each party must file a pre-merger notification with the Federal Trade Commission, which is referred to in this joint proxy statement/

prospectus as the FTC, and the Antitrust Division of the Department of Justice, which is referred to in this joint proxy statement/prospectus as the DOJ. A transaction notifiable under the HSR Act may not be completed until the expiration of a 30-calendar-day waiting period following the parties’ filings of their respective HSR Act notification forms or the termination of that waiting period. If the DOJ issues a Request for Additional Information and Documentary Material prior to the expiration of the initial waiting period, the parties must observe a second 30-calendar-day waiting period, which would begin to run only after both parties have substantially complied with the request for additional information, unless the waiting period is terminated earlier.

Both Comcast and TWC are subject to regulation by the FCC under the Communications Act of 1934, as amended, which is referred to in this joint proxy statement/prospectus as the Communications Act. Each company holds a number of licenses and authorizations issued by the FCC for the operation of its business. The FCC must approve the transfer of control or assignment of TWC’s licenses and authorizations to Comcast as a result of the merger. The merger is also subject to the approval of LFAs with respect to the transfer of control of franchises as a result of the merger. In addition, Comcast and TWC are required to obtain approval of certain state public utility commissions with respect to the transfer of control of certificates of public convenience and necessity for telecommunications services as a result of the merger.

Comcast and TWC have agreed to use their respective reasonable best efforts to obtain all regulatory approvals required to complete the merger. In furtherance of the foregoing, Comcast and TWC have agreed to make and not withdraw (i) as promptly as practicable (and not later than 30 business days following the date of the merger agreement), an appropriate filing of a Notification and Report Form pursuant to the HSR Act and all necessary filings to obtain consents from the FCC that are required in connection with the merger, and (ii) as promptly as practicable (and not later than 60 business days following the date of the merger agreement), all necessary filings to obtain consents from state regulators and franchise authorities (including submitting FCC Forms 394 to relevant franchise authorities), and all other registrations, declarations, notices and filings with governmental authorities that are required in connection with the merger. The process for obtaining the requisite regulatory approvals is ongoing.

Comcast’s obligation to use reasonable best efforts to obtain all regulatory approvals required to complete the merger does not require Comcast to (and, without Comcast’s prior written consent, TWC is not permitted to):

Notwithstanding the first two bullets above, (i) Comcast is prepared to divest up to approximately three million subscribers of the combined company and (ii) Comcast and its subsidiaries are required under the merger agreement to (A) take the actions and accept the conditions described in the second bullet above to the extent such actions and conditions are consistent in scope and magnitude with the actions and conditions (other than any condition that was subsequently suspended by the agency that imposed the condition) required or imposed by governmental authorities in connection with prior acquisitions of United States domestic cable systems consummated within the past twelve years with an aggregate purchase price of at least $500 million and (B) implement certain undertakings agreed to by TWC and Comcast described in “TWC Proposal I: Adoption of the Merger Agreement and Comcast Proposal I: Approval of the Stock Issuance—Regulatory Approvals Required for the Merger—Efforts to Obtain Regulatory Approvals” beginning on page [—] of this joint proxy statement/prospectus, with such modifications to the undertakings that, taken in the aggregate, are no more adverse to the businesses, assets and properties of Comcast and its subsidiaries, taken as a whole, or the businesses, assets and properties of TWC and its subsidiaries taken as a whole. Further, notwithstanding the third bullet above, Comcast has agreed to participate in the litigation of proceedings involving the FCC or the DOJ to

the extent Comcast determines in its reasonable good faith judgment that there is a reasonable prospect of success in relation to such litigation and that the participation by Comcast in such litigation would not pose a material risk of the imposition of a burdensome condition. These requirements are described in more detail under “The Merger Agreement—Reasonable Best Efforts Covenant” beginning on page [—] of this joint proxy statement/prospectus.

Subject to certain exceptions set forth on the confidential disclosure schedules, Comcast and TWC have agreed not to, and to cause their respective subsidiaries and affiliates not to, (i) take any action that would reasonably be expected to have the effect of materially delaying, impairing or impeding the receipt of any regulatory approvals required in connection with the transactions contemplated by the merger agreement or the completion of the merger, or (ii) acquire (by merger, consolidation, acquisition of stock or assets or otherwise), directly or indirectly, any assets, securities (other than securities issued by such party as permitted by the terms of the merger agreement), properties, interests or business in any transaction or series of related transactions if such acquisition would (A) require approval of the FCC or (B) (without the consent of the other party, not to be unreasonably withheld, conditioned or delayed in the case of TWC’s consent) have a value, or involve the payment of consideration, in excess of $1 billion.

The Merger Is Expected to be Completed by the End of 2014 (See Page [—])

The merger will occur no later than two business days after the conditions to its completion have been satisfied or, to the extent permitted by applicable law, waived, unless otherwise mutually agreed by the parties. As of the date of this joint proxy statement/prospectus, the merger is expected to be completed by the end of 2014. However, there can be no assurance as to when, or if, the merger will occur.

Subject to certain conditions described below, if the merger is not completed on or before February 12, 2015, which is referred to in this joint proxy statement/prospectus as the initial end date, or, at the election of either Comcast or TWC if certain conditions related to the receipt of regulatory approvals have not been satisfied, by August 12, 2015, either Comcast or TWC may terminate the merger agreement.

No Solicitation by TWC (See Page [—])

As more fully described in this joint proxy statement/prospectus and in the merger agreement, and subject to the exceptions described below, TWC has agreed that neither TWC nor any of its subsidiaries will, nor will TWC or any of its subsidiaries authorize or permit any of its or their officers, directors, employees or representatives to (i) solicit, initiate or take any action to knowingly facilitate or encourage the submission of an acquisition proposal (as defined under “The Merger Agreement—No Solicitation by TWC,” beginning on page [—] of this joint proxy statement/prospectus), (ii) enter into or participate in any discussions or negotiations regarding any such proposal, (iii) furnish any non-public information relating to TWC or its subsidiaries to any third party that is seeking to make, or has made, an acquisition proposal, (iv) except as described below, fail to make, withdraw or modify in a manner adverse to Comcast the recommendation of the TWC board of directors in favor of adoption of the merger agreement or recommend an acquisition proposal (any action described in this clause (iv) is referred to in this joint proxy statement/prospectus as an adverse recommendation change), (v) fail to enforce or grant any waiver or release under any standstill or similar agreement, (vi) approve any transaction under, or any person becoming an “interested stockholder” under, the Delaware anti-takeover statute, or (vii) enter into an agreement or other instrument relating to an acquisition proposal. However, so long as TWC and its representatives have otherwise complied with the foregoing requirements, TWC and its representatives may, at any time prior to adoption of the merger agreement by TWC stockholders, participate in discussions with any third party who has made an unsolicited acquisition proposal after the date of the merger agreement solely to request the clarification of the terms and conditions of the proposal so as to determine whether such proposal is, or could reasonably be expected to lead to, a superior proposal (as defined under “The Merger Agreement—No Solicitation by TWC,” beginning on page [—] of this joint proxy statement/prospectus).

Notwithstanding the foregoing, at any time prior to the adoption of the merger agreement by TWC stockholders, subject to the terms and conditions described in the merger agreement, TWC is permitted to:

TWC is only permitted to take the actions described above if the TWC board of directors determines in good faith, after considering advice from outside legal counsel, that the failure to take that action would be inconsistent with its fiduciary duties under applicable law. In addition, before taking any of the actions described above, TWC has to notify Comcast that it intends to take that action and continue to advise Comcast on a current basis of the status and terms of any discussions and negotiations with any third party in connection with an acquisition proposal. Further, the TWC board of directors is not permitted to make an adverse recommendation change in response to an acquisition proposal unless, (i) such acquisition proposal constitutes a superior proposal, (ii) TWC promptly notifies Comcast, in writing at least five business days before taking that action, of its intention to do so, and attaches the most current version of the proposed agreement under which such superior proposal is proposed to be consummated and the identity of the third party making the superior proposal, and (iii) Comcast does not make, within such five business day period, an offer that is at least as favorable to the stockholders of TWC as such superior proposal.

In addition, the TWC board of directors is not permitted to make an adverse recommendation change in response to an intervening event unless (i) TWC has provided Comcast with written information describing the intervening event in reasonable detail promptly after becoming aware of it and keeps Comcast fully informed, on a reasonably current basis, of material developments with respect to such intervening event, (ii) TWC has provided Comcast at least five business days prior notice of its intention to make an adverse recommendation change with respect to such intervening event, attaching a reasonably detailed explanation of the facts underlying the determination by the TWC board of directors that an intervening event has occurred and its need to make an adverse recommendation change in light of the intervening event and (iii) Comcast does not make, within such five-business-day period, an offer that the TWC board of directors determines would obviate the need for an adverse recommendation change in light of the intervening event.

During any five-business-day period prior to effecting an adverse recommendation change in response to an acquisition proposal or an intervening event, TWC and its representatives must negotiate in good faith with Comcast and its representatives regarding any revisions to the terms of the transactions contemplated by the merger agreement proposed by Comcast.

If the TWC board of directors withdraws, modifies or qualifies its recommendation in favor of adoption of the merger agreement, the merger agreement must nonetheless be submitted to TWC’s stockholders for adoption, unless the merger agreement has been terminated in accordance with its terms. See “The Merger Agreement— Obligation of the TWC Board of Directors to Recommend the Merger Agreement and Call and Hold a Stockholders’ Meeting” beginning on page [—] of this joint proxy statement/prospectus.

Termination of the Merger Agreement (See Page [—])

As more fully described in this joint proxy statement/prospectus and in the merger agreement, and subject to the terms and conditions described in the merger agreement, the merger agreement may be terminated at any time before completion of the merger in any of the following ways:

Specific Performance; Remedies (See Page [—])

Under the merger agreement, each of Comcast and TWC is entitled to an injunction or injunctions to prevent breaches of the merger agreement or to enforce specifically the terms and provisions of the merger agreement, in addition to any other remedy to which that party may be entitled at law or in equity.

Material U.S. Federal Income Tax Consequences of the Merger (See Page [—])

Comcast and TWC have structured the merger as a “tax-free” reorganization for U.S. federal income tax purposes. Accordingly, TWC stockholders will generally not recognize any gain or loss for U.S. federal income tax purposes on the exchange of their shares of TWC common stock for Comcast common stock in the merger, except for any gain or loss recognized in connection with any cash received in lieu of fractional Comcast shares. The companies themselves will not recognize gain or loss as a result of the merger. It is a condition to the obligations of TWC and Comcast to complete the merger that each receive a legal opinion from its respective outside counsel that the merger will be a reorganization for U.S. federal income tax purposes and that Comcast, Merger Sub and TWC will each be a party to that reorganization.

Accounting Treatment (See Page [—])

The merger will be accounted for using the acquisition method of accounting with Comcast considered the acquirer of TWC. Comcast will record assets acquired, including identifiable intangible assets, and liabilities assumed from TWC at their respective fair values at the date of completion of the merger. Any excess of the purchase price (as described under Note 1 of the “Comcast and TWC Unaudited Pro Forma Condensed Combined Financial Statements” beginning on page [—] of this joint proxy statement/prospectus) over the net fair value of such assets and liabilities will be recorded as goodwill.

Rights of TWC Stockholders Will Change as a Result of the Merger (See Page [—])

TWC stockholders will have different rights once they become Comcast shareholders due to differences between the organizational documents of Comcast and TWC and differences between Pennsylvania law, where Comcast is incorporated, and Delaware law, where TWC is incorporated. These differences are described in more detail under “Comparison of Stockholder Rights” beginning on page [—] of this joint proxy statement/prospectus.

Litigation Relating to the Merger (See Page [—])

Following the announcement of the merger, eight putative class action complaints challenging the merger have been filed on behalf of purported TWC stockholders, seven in the Supreme Court of the State of New York, County of New York and one in the Court of Chancery of the State of Delaware. The complaints generally allege, among other things, that the members of the TWC board of directors breached their fiduciary duties to TWC stockholders during merger negotiations and by entering into the merger agreement and approving the merger, and that TWC, Comcast and Merger Sub aided and abetted such breaches of fiduciary duties.

The defendants believe that the claims asserted against them in the lawsuits are without merit and intend to defend the litigation vigorously. The litigation is described in more detail under “TWC Proposal I: Adoption of the Merger Agreement and Comcast Proposal I: Approval of the Stock Issuance—Litigation Relating to the Merger” beginning on page [—] of this joint proxy statement/prospectus.

SELECTED HISTORICAL CONSOLIDATED FINANCIAL DATA OF COMCAST

The following table presents selected historical consolidated financial data of Comcast. The selected financial data of Comcast for each of the years ended December 31, 2013, 2012 and 2011, and as of December 31, 2013 and 2012 are derived from Comcast’s audited consolidated financial statements and related notes contained in its Annual Report on Form 10-K for the year ended December 31, 2013, which is referred to in this joint proxy statement/prospectus as the Comcast 2013 10-K, and which is incorporated by reference into this joint proxy statement/prospectus. The selected financial data of Comcast for each of the years ended December 31, 2010 and 2009, and as of December 31, 2011, 2010 and 2009, have been derived from Comcast’s audited consolidated financial statements for such years, which have not been incorporated by reference into this joint proxy statement/prospectus.

SELECTED HISTORICAL CONSOLIDATED FINANCIAL DATA OF TWC

The following table presents selected historical consolidated financial data of TWC. The selected financial data of TWC for each of the years ended December 31, 2013, 2012 and 2011, and as of December 31, 2013 and 2012, are derived from TWC’s audited consolidated financial statements and related notes contained in its Annual Report on Form 10-K for the year ended December 31, 2013, which is referred to in this joint proxy statement/prospectus as the TWC 2013 10-K, and which is incorporated by reference into this joint proxy statement/prospectus. The selected financial data of TWC for each of the years ended December 31, 2010 and 2009, and as of December 31, 2011, 2010 and 2009, have been derived from TWC’s audited consolidated financial statements for such years, which have not been incorporated by reference into this joint proxy statement/prospectus.

COMPARATIVE HISTORICAL AND UNAUDITED PRO FORMA PER SHARE DATA

The following table sets forth selected historical and unaudited pro forma combined per share information for Comcast and TWC.

Historical Per Share Information of Comcast and TWC

The historical per share information of each of Comcast and TWC below is derived from the audited consolidated financial statements of each of Comcast and TWC as of, and for the year ended, December 31, 2013.

Unaudited Pro Forma Combined per Comcast Common Share Data

The unaudited pro forma combined per Comcast common share data set forth below gives effect to the merger under the acquisition method of accounting, as if the merger had been effective on January 1, 2013, the first day of Comcast’s fiscal year ended December 31, 2013, in the case of net income, and at December 31, 2013, in the case of book value per share data, and assuming that each outstanding share of TWC common stock had been converted into Comcast common shares based on the exchange ratio.

The unaudited pro forma combined per Comcast common share data is derived from the audited consolidated financial statements of each of Comcast and TWC as of, and for the year ended, December 31, 2013.

The acquisition method of accounting is based on Financial Accounting Standards Board, Accounting Standards Codification, which is referred to in this joint proxy statement/prospectus as ASC, 805, “Business Combinations,” and uses the fair value concepts defined in ASC 820, “Fair Value Measurements and Disclosures,” which Comcast has adopted as required. Acquisition accounting requires, among other things, that assets acquired and liabilities assumed be recognized at their fair values as of the acquisition date. Fair value measurements recorded in acquisition accounting are dependent upon detailed valuation studies of TWC’s assets and liabilities and other studies that have yet to commence. Accordingly, the pro forma adjustments reflect the assets and liabilities of TWC at their preliminary estimated fair values. Differences between these preliminary estimates and the final values in acquisition accounting will occur and these differences could have a material impact on the unaudited pro forma combined per share information set forth in the following table.

The unaudited pro forma combined per Comcast common share data does not purport to represent the actual results of operations that Comcast would have achieved had the companies been combined during these periods or to project the future results of operations that Comcast may achieve after the merger.

Unaudited Pro Forma Combined per TWC Equivalent Share Data

The unaudited pro forma combined per TWC equivalent share data set forth below shows the effect of the merger from the perspective of an owner of TWC common stock. The information was calculated by multiplying the unaudited pro forma combined per Comcast common share amounts by the exchange ratio.

Generally

You should read the below information in conjunction with the selected historical consolidated financial information included elsewhere in this joint proxy statement/prospectus and the historical consolidated financial statements of Comcast and TWC and related notes that have been filed with the SEC, certain of which are incorporated by reference into this joint proxy statement/prospectus. See “Selected Historical Consolidated

Financial Data of Comcast,” “Selected Historical Consolidated Financial Data of TWC” and “Where You Can Find More Information” beginning on pages [—], [—] and [—], respectively, of this joint proxy statement/prospectus. The unaudited pro forma combined per Comcast common share data and the unaudited pro forma combined per TWC equivalent share data is derived from, and should be read in conjunction with, the Comcast and TWC unaudited pro forma condensed combined financial statements and related notes included in this joint proxy statement/prospectus. See “Comcast and TWC Unaudited Pro Forma Condensed Combined Financial Statements” beginning on page [—] of this joint proxy statement/prospectus.

COMPARATIVE PER SHARE MARKET PRICE AND DIVIDEND INFORMATION

Market Prices

The following table sets forth, for the calendar periods indicated, the high and low intra-day sales prices per share of Comcast Class A common stock and Comcast Class A Special common stock and per share of TWC common stock. Comcast Class A common stock is listed on NASDAQ under the symbol CMCSA, and Comcast Class A Special common stock is listed on NASDAQ under the symbol CMCSK. There is no established public trading market for Comcast Class B common stock. The Comcast Class B common stock can be converted, on a share-for-share basis, into Comcast Class A common stock or Comcast Class A Special common stock. TWC’s common stock is listed on the New York Stock Exchange under the symbol TWC.

The following table sets forth the closing price per share of Comcast Class A common stock and Comcast Class A Special common stock and of TWC common stock as of February 12, 2014, the last trading day before the public announcement of the merger agreement, and as of [—], 2014, the most recent practicable trading day prior to the date of this joint proxy statement/prospectus. The table also shows the implied value of the merger consideration proposed for each share of TWC common stock as of the same two dates. This implied value was calculated by multiplying the closing price of a share of Comcast Class A common stock on the relevant date by the exchange ratio of 2.875.

The market prices of shares of Comcast Class A common stock and Comcast Class A Special common stock and TWC common stock have fluctuated since the date of the announcement of the merger agreement and will continue to fluctuate from the date of this joint proxy statement/prospectus to the date of the TWC special meeting and the date the merger is completed and thereafter. No assurance can be given concerning the market prices of Comcast Class A common stock and Comcast Class A Special common stock and TWC common stock before completion of the merger or Comcast Class A common stock or Comcast Class A Special common stock after completion of the merger. The exchange ratio is fixed in the merger agreement, but the market price of Comcast Class A common stock (and therefore the value of the merger consideration) when received by TWC stockholders after the merger is completed could be greater than, less than or the same as shown in the table above. Accordingly, TWC stockholders are advised to obtain current market quotations for Comcast Class A common stock and TWC common stock in deciding whether to vote for adoption of the merger agreement.

Dividends

Comcast currently pays a quarterly dividend on Comcast common shares and last paid a quarterly dividend on January 23, 2014, of $0.195 per share. In addition, on January 28, 2014, Comcast declared a quarterly dividend of $0.225 per share, which will be paid on April 23, 2014 to Comcast shareholders of record at the close of business on April 2, 2014. Under the terms of the merger agreement, during the period before completion of the merger, Comcast is not permitted to declare, set aside or pay any dividend or other distribution other than its regular cash dividend in the ordinary course of business consistent with past practice in an amount not to exceed $0.225 per share per quarter in 2014, as such amount may be increased for 2015 in the ordinary course of business consistent with past practice.

TWC currently pays a quarterly dividend on TWC common stock, and last paid a quarterly dividend on March 17, 2014, of $0.75 per share. Under the terms of the merger agreement, during the period before completion of the merger, TWC is not permitted to declare, set aside or pay any dividend or other distribution other than its regular cash dividend in the ordinary course of business consistent with past practice in an amount not to exceed $0.75 per share per quarter in 2014, as such amount may be increased for 2015 in the ordinary course of business consistent with past practice.

In addition, the merger agreement provides that Comcast and TWC will coordinate the declaration of dividends in order that holders of shares of Comcast Class A common stock and TWC common stock do not receive two dividends or fail to receive one dividend for any quarter in respect of shares of TWC common stock, on the one hand, and shares of Comcast Class A common stock issuable in respect of such shares of TWC common stock, on the other hand.

Any former TWC stockholder who holds the Comcast Class A common stock into which TWC common stock has been converted in connection with the merger will receive whatever dividends are declared and paid on Comcast Class A common stock after completion of the merger. However, no dividend or other distribution having a record date after completion of the merger will actually be paid with respect to any Comcast Class A common stock into which TWC common stock has been converted in connection with the merger until the certificates formerly representing shares of TWC common stock have been surrendered (or the book-entry shares formerly representing shares of TWC common stock have been transferred), at which time any accrued dividends and other distributions on those shares of Comcast Class A common stock will be paid without interest. Subject to the limitations set forth in the merger agreement, any future dividends by Comcast will be made at the discretion of the Comcast board of directors. Subject to the limitations set forth in the merger agreement, any future dividends by TWC will be made at the discretion of the TWC board of directors. There can be no assurance that any future dividends will be declared or paid by Comcast or TWC or as to the amount or timing of those dividends, if any.

COMCAST AND TWC UNAUDITED

PRO FORMA CONDENSED COMBINED FINANCIAL STATEMENTS

The following Comcast and TWC unaudited pro forma condensed combined financial statements, which are referred to in this joint proxy statement/prospectus as the unaudited pro forma financial information, gives effect to the proposed merger in which TWC will become a 100% owned subsidiary of Comcast. The Unaudited Pro Forma Condensed Combined Balance Sheet is presented as if the merger had closed on December 31, 2013. The Unaudited Pro Forma Condensed Combined Statement of Income is presented as if the merger had closed on January 1, 2013. The unaudited pro forma financial information is based on the historical consolidated financial statements of Comcast and TWC, and the assumptions and adjustments set forth in the accompanying explanatory notes.

The unaudited pro forma financial information was prepared using the acquisition method of accounting with Comcast treated as the accounting acquirer and, therefore, the historical basis of Comcast’s assets and liabilities was not affected by the merger. The unaudited pro forma financial information has been developed from and should be read in conjunction with the Comcast and TWC audited consolidated financial statements and related notes contained in the Comcast 2013 10-K and the TWC 2013 10-K, which are incorporated by reference into this joint proxy statement/prospectus. For purposes of developing the Unaudited Pro Forma Condensed Combined Balance Sheet as of December 31, 2013, TWC’s assets, including identifiable intangible assets, and liabilities have been recorded at their estimated fair values and the excess purchase price has been assigned to goodwill. The fair values assigned in this unaudited pro forma financial information are preliminary and represent Comcast management’s best estimate of fair value and are subject to revision. The unaudited pro forma financial information is provided for illustrative purposes only and is based on available information and assumptions that Comcast believes are reasonable. It does not purport to represent what the actual consolidated results of operations or the consolidated financial position of Comcast would have been had the merger occurred on the dates indicated, nor is it necessarily indicative of future consolidated results of operations or consolidated financial position. The actual financial position and results of operations will differ, perhaps significantly, from the pro forma amounts reflected herein due to a variety of factors, including access to additional information, changes in value not currently identified and changes in operating results following the date of the unaudited pro forma financial information.

Comcast announced that it is prepared to divest systems serving up to approximately three million customers in order to address potential concerns of regulators. There is no commitment or probable transaction related to these potential divestitures, no specific systems have been identified and the manner in which any potential divestitures might be effected has not been determined. As such, the unaudited pro forma financial information does not include adjustments to give effect to any potential divestitures.

Comcast intends to review the synergies of the combined business, which may result in a plan to realign or reorganize certain of TWC’s existing operations. The costs of implementing such a plan, if it was to occur, and any resulting future cost savings have not been reflected in the accompanying unaudited pro forma financial information.

Upon closing of the merger, TWC stockholders will receive 2.875 shares of Comcast Class A common stock in exchange for each share of TWC common stock. For purposes of this unaudited pro forma financial information, giving effect to the exchange ratio described above, the estimated aggregate consideration to complete the merger would have been $41.3 billion based upon a per share price of $50.64, the closing price of shares of Comcast Class A common stock on March 14, 2014, and 278.3 million shares of TWC common stock outstanding as of March 14, 2014. ASC 805, “Business Combinations,” requires that the consideration transferred be measured at the date the merger is completed at the then-current market price. This requirement

will likely result in a total consideration that is different from the amount assumed in these unaudited pro forma condensed combined financial statements. Based on the 278.3 million shares of TWC common stock outstanding as of March 14, 2014 and the fixed exchange ratio described above, each dollar increase (decrease) in the per share price of the Comcast Class A common stock will result in a $800 million increase (decrease) in the total consideration for the transaction, substantially all of which Comcast expects would be recorded as an increase (decrease) in the amount of goodwill recorded in the transaction. The outstanding number of shares of TWC common stock will change prior to the closing of the merger due to transactions in the ordinary course, including the vesting of outstanding TWC equity awards. These changes are not expected to have a material effect on this unaudited pro forma financial information.

Unaudited Pro Forma Condensed Combined Balance Sheet

As of December 31, 2013

See accompanying notes to unaudited pro forma financial information.

Unaudited Pro Forma Condensed Combined Statement of Income

For the Year Ended December 31, 2013

See accompanying notes to unaudited pro forma financial information.

Notes to Unaudited Pro Forma Financial Information

Note 1. Basis of Presentation

On February 12, 2014, Comcast and TWC entered into the merger agreement which provides for a merger in which TWC will become a 100% owned subsidiary of Comcast. If the merger is completed, TWC stockholders will have the right to receive, in exchange for each share of TWC common stock owned immediately prior to the merger, 2.875 shares of Comcast Class A common stock. Upon completion of the merger, TWC stock options and other equity awards will generally convert into stock options and equity awards with respect to Comcast Class A common stock, after giving effect to the exchange ratio. The exchange ratio is fixed and will not be adjusted for changes in the market value of shares of Comcast Class A common stock or TWC common stock. Because the exchange ratio was fixed at the time the merger agreement was executed and because the market value of Comcast Class A common stock and TWC common stock will continue to fluctuate, TWC stockholders cannot be sure of the value of the shares of Comcast Class A common stock they will receive relative to the value of their shares of TWC common stock and will likely result in a per share equity component different from the $50.64 closing price of Comcast Class A common stock on March 14, 2014 that is assumed for purposes of this unaudited pro forma financial information, and that difference may be material.

The merger will be accounted for using the acquisition method of accounting with Comcast considered the acquirer of TWC.

The accompanying unaudited pro forma financial information is intended to reflect the impact of the merger on Comcast’s consolidated financial statements and presents the pro forma consolidated financial position and results of operations of Comcast based on the historical financial statements of Comcast and TWC after giving effect to the merger and pro forma adjustments as described in these notes. Pro forma adjustments are included only to the extent they are (i) directly attributable to the merger, (ii) factually supportable and (iii) with respect to the statement of income, expected to have a continuing impact on the combined results. The accompanying unaudited pro forma financial information is presented for illustrative purposes only and does not reflect the costs of any integration activities or benefits that may result from realization of future cost savings due to operating efficiencies or synergies expected to result from the merger.

The Unaudited Pro Forma Condensed Combined Balance Sheet gives effect to the merger as if it had occurred on December 31, 2013, and the Unaudited Pro Forma Condensed Combined Statement of Income gives effect to the merger as if it had occurred on January 1, 2013.

Fair Value Adjustments

The unaudited pro forma financial information reflects the preliminary assessment of fair values and lives assigned to the assets acquired and liabilities assumed. Fair value estimates were determined based on preliminary discussions between Comcast and TWC management, due diligence efforts and information available in public filings. The detailed valuation studies necessary to arrive at the required estimates of the fair values for the TWC assets acquired and liabilities assumed have not commenced. Significant assets and liabilities that are subject to preparation of valuation studies to determine appropriate fair value adjustments include property and equipment, identifiable intangible assets, including franchise rights, and debt obligations. Changes to the fair values of these assets and liabilities will also result in changes to deferred tax liabilities.

Purchase Price

The Unaudited Pro Forma Condensed Combined Balance Sheet has been adjusted to reflect the estimated fair values of the identifiable assets acquired and liabilities assumed and the excess of the consideration over these fair values is recorded to goodwill. The fair value of the consideration, or the purchase price, in the

unaudited pro forma financial information is approximately $41.3 billion. This amount was derived based on the outstanding shares of TWC common stock at March 14, 2014, the exchange ratio and a price per share of Comcast Class A common stock of $50.64, which represents the closing price on March 14, 2014. The actual number of shares of Comcast Class A common stock issued to TWC stockholders upon closing of the merger will be based on the actual number of shares of TWC common stock outstanding when the merger closes, and the valuation of those shares will be based on the trading price of Comcast Class A common stock at that time. TWC equity awards outstanding at the time of the closing of the merger will be assumed by Comcast. TWC equity awards held by current employees will be converted into equity awards with respect to Comcast Class A common stock, after giving effect to the 2.875 exchange ratio. The terms of these awards, including vesting provisions, will generally be identical to those of the historical TWC equity awards. TWC equity awards held by non-employees, whether or not vested, will be canceled and the holders will be entitled to cash in an amount equal to the value of the equity awards as if they were converted on the basis described above. The fair value of vested equity awards held by employees and equity awards held by non-employees, whether or not vested, will be considered part of the purchase price. Accordingly, the purchase price includes estimated fair values for employee and non-employee TWC equity awards of $574 million and $177 million, respectively.

The table below presents the preliminary purchase price as if the merger had closed on December 31, 2013, along with a preliminary allocation of purchase price to the assets acquired and liabilities assumed:

Preliminary Purchase Price

Preliminary Allocation of Purchase Price

Upon completion of the fair value assessment following the merger, Comcast anticipates the ultimate fair values of the net assets acquired will differ from the preliminary assessment outlined above. Generally, changes to the initial estimates of the fair value of the assets and liabilities will be recorded as adjustments to those assets and liabilities and residual amounts will be allocated to goodwill.

Other Transaction-related Adjustments

The unaudited pro forma financial information reflects certain reclassifications of TWC balance sheet and statement of income categories to conform to Comcast’s presentation.

The unaudited pro forma financial information reflects certain adjustments to eliminate transactions between Comcast and TWC.

The unaudited pro forma financial information does not reflect any adjustments to conform TWC’s accounting policies to those adopted by Comcast as no such adjustments were identified that would have a material effect on the unaudited pro forma financial information.

Further review may identify additional reclassifications, intercompany transactions or differences between the accounting policies of the two companies that, when conformed, could have a material impact on the unaudited pro forma financial information of the combined company. At this time, Comcast and TWC are not aware of any reclassifications, intercompany transactions or accounting policy differences that would have a material impact on the unaudited pro forma financial information that are not reflected in the pro forma adjustments.

Items Not Adjusted in the Unaudited Pro Forma Financial Information

The unaudited pro forma financial information does not include any adjustment for liabilities or related costs that may result from integration activities, since management is in the process of making these assessments. Significant liabilities and related costs may ultimately be recorded for employee severance or relocation, costs of vacating some facilities and costs associated with other exit and integration activities.

Comcast and TWC anticipate that the merger will result in significant annual operating synergies that would be unachievable without completing the transaction. No assurance can be made that Comcast will be able to achieve these synergies and any such synergies have not been reflected in the unaudited pro forma financial information.

The Unaudited Pro Forma Condensed Combined Statement of Income does not include any material nonrecurring charges that might arise as a result of the merger, including supplemental bonuses. The Unaudited Pro Forma Condensed Combined Balance Sheet only includes adjustments for transaction-related costs that are factually supportable.

Comcast announced that it is prepared to divest systems serving up to approximately three million customers in order to address potential concerns of regulators. There is no commitment or probable transaction related to these potential divestitures, no specific systems have been identified and the manner in which any potential divestitures might be effected has not been determined. As such, the unaudited pro forma financial information does not include adjustments to give effect to any potential divestitures.

Comcast and TWC each have investments in certain entities which are accounted for under the equity method of accounting. As a result of the merger, these entities may be required to be consolidated as a result of the governance structure at that time. The consolidation of these entities has not been reflected in the unaudited pro forma financial information because it is not expected to have a material effect on the unaudited pro forma financial information. The values of these and other TWC investments and TWC’s noncontrolling interests have not been adjusted to fair value in the unaudited pro forma financial information as the valuation studies necessary to arrive at the required estimates of fair value have not commenced.

The merger may result in a change in Comcast’s tax rate used to determine deferred income taxes due to changes in apportionment factors related to state income taxes. Any changes in Comcast’s deferred taxes as a

result of the merger will be reflected in income as of the closing date. The unaudited pro forma financial information does not include the impact of any such changes on Comcast’s existing deferred tax assets and liabilities as the analysis is not complete.

Note 2. Transaction-related Adjustments

The unaudited pro forma financial information reflects the following adjustments: