SUMMARY

This summary highlights selected information from this proxy statement/prospectus. It may not contain all of the information that is important to you. You are urged to read carefully the entire proxy statement/prospectus and the other documents referred to in this 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 proxy statement/prospectus. Each item in this summary refers to the page of this proxy statement/prospectus on which that subject is discussed in more detail.

The Companies (See Page [—])

Aetna Inc.

Aetna was incorporated in the Commonwealth of Pennsylvania in 1982. Aetna is one of the nation’s leading diversified health care benefits companies, serving approximately 36.7 million people as of June 30, 2012, with information and resources to help them make better informed decisions about their health care. Aetna offers a broad range of traditional and consumer-directed health insurance products and related services, including medical, pharmacy, dental, behavioral health, group life and disability plans, medical management capabilities, Medicaid health care management services and health information exchange technology services. Aetna’s customers include employer groups, individuals, college students, part-time and hourly workers, health plans, health care providers, governmental units, government-sponsored plans, labor groups and expatriates.

The principal trading market for Aetna common shares (NYSE: AET) is the New York Stock Exchange. The principal executive offices of Aetna are located at 151 Farmington Avenue, Hartford, CT 06156; its telephone number is (860) 273-0123; and its website is www.aetna.com.

This proxy statement/prospectus incorporates important business and financial information about Aetna from other documents that are not included in or delivered with this 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 proxy statement/prospectus.

Coventry Health Care, Inc.

Coventry was incorporated in the State of Delaware on December 17, 1997, and is the successor to Coventry Corporation, which was incorporated in the State of Delaware on November 21, 1986.

Coventry is a diversified national managed health care company based in Bethesda, Maryland, dedicated to delivering high-quality health care solutions at an affordable price. Coventry provides a full portfolio of risk and fee-based products, including Medicare and Medicaid programs, group and individual health insurance, workers’ compensation solutions, and network rental services. With a presence in every state in the nation, Coventry’s products currently serve approximately five million individuals, helping them receive the greatest possible value for their health care investment.

The principal trading market for Coventry common stock (NYSE: CVH) is the New York Stock Exchange. The principal executive offices of Coventry are located at 6720-B Rockledge Drive, Suite 700, Bethesda, MD 20817; its telephone number is (301) 581-0600; and its website is www.coventryhealthcare.com.

This proxy statement/prospectus incorporates important business and financial information about Coventry from other documents that are not included in or delivered with this 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 proxy statement/prospectus.

Jaguar Merger Subsidiary, Inc.

Merger Sub was incorporated in the State of Delaware on August 16, 2012, and is a wholly owned subsidiary of Aetna. Merger Sub was formed solely for the purpose of completing a merger with Coventry. 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 151 Farmington Avenue, Hartford, CT 06156; and its telephone number is (860) 273-0123.

The Merger (See Page [—])

Aetna, Merger Sub and Coventry 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 Coventry, with Coventry continuing as the surviving corporation. Upon completion of the merger, Coventry will be a wholly owned subsidiary of Aetna, and Coventry common stock will no longer be outstanding or publicly traded.

A copy of the merger agreement is attached as Annex A to this 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 Coventry (See Page [—])

Meeting. The Coventry special meeting will be held on [—], 2012, at [—], [—], at [—], local time. At the Coventry special meeting, Coventry stockholders will be asked to consider and vote on the following proposals:

Record Date. The Coventry board of directors has fixed the close of business on [—], 2012, as the record date for determination of the stockholders entitled to vote at the Coventry special meeting or any adjournment or postponement thereof. Only Coventry stockholders of record at the record date are entitled to receive notice of, and to vote at, the Coventry special meeting or any adjournment or postponement of the Coventry special meeting. As of the close of business on [—], 2012, there were [—] shares of Coventry common stock outstanding. Each holder of Coventry common stock is entitled to one vote for each share of Coventry common stock owned at the record date.

Quorum. The presence at the Coventry special meeting, in person or by proxy, of the holders of a majority of the aggregate voting power of Coventry common stock outstanding at the record date (the close of business on [—], 2012) and otherwise entitled to vote will constitute a quorum. An abstention or broker non-vote each will be included in determining the number of shares present and entitled to vote at the Coventry special meeting for the purpose of determining the presence of a quorum. There must be a quorum for business to be conducted at the Coventry special meeting. Failure of a quorum to be represented at the Coventry special meeting will necessitate an adjournment or postponement and will subject Coventry to additional expense.

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

To approve the adjournment of the Coventry special meeting if necessary to solicit additional proxies if there are not sufficient votes to adopt the merger agreement at the time of the Coventry special meeting, the affirmative vote of holders of a majority of the shares of Coventry common stock present in person or represented by proxy at the Coventry special meeting and entitled to vote on the proposal is required. Because approval of this proposal requires the affirmative vote of holders of a majority of the shares present in person or represented by proxy and entitled to vote, an abstention will have the same effect as a vote “AGAINST” the proposal to adjourn the Coventry special meeting. A broker non-vote or other failure to vote will have no effect on the outcome of any vote to adjourn the Coventry special meeting.

To approve, on an advisory (non-binding) basis, “golden parachute” compensation payments that will or may be paid by Coventry to its named executive officers in connection with the merger, the affirmative vote of holders of a majority of the shares of Coventry common stock present in person or represented by proxy at the Coventry special meeting and entitled to vote on the proposal is required. Because approval of this proposal requires the affirmative vote of holders of a majority of the shares present in person or represented by proxy and entitled to vote, an abstention will have the same effect as a vote “AGAINST” the “golden parachute” compensation proposal. A broker non-vote or 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 Coventry Directors and Executive Officers. At the record date for the Coventry special meeting (the close of business on [—], 2012), Coventry’s directors and executive officers and their affiliates beneficially owned and had the right to vote [—] shares of Coventry common stock at the Coventry special meeting, which represents approximately [—]% of the shares of Coventry common stock entitled to vote at the Coventry special meeting.

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

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

If the merger is completed, Coventry stockholders will be entitled to receive, in exchange for each share of Coventry common stock that they own immediately prior to the merger, $27.30 in cash, without interest, and 0.3885 of an Aetna common share, which, together with cash payable in lieu of any fractional shares as described below, are collectively referred to in this proxy statement/prospectus as the merger consideration.

Aetna will not issue any fractional shares in the merger. Instead, the total number of Aetna common shares that each Coventry stockholder will receive in the merger will be rounded down to the nearest whole number, and each Coventry stockholder will receive cash, without interest, for any fractional Aetna common share 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 an Aetna common share that the Coventry stockholder would otherwise be entitled to receive in the merger by the average of the volume weighted averages of the trading prices for Aetna common shares on the New York Stock Exchange for each of the five trading days ending on the trading day that is two trading days prior to completion of the merger, which average is referred to in this proxy statement/prospectus as the Aetna closing price.

Example: If you own 100 shares of Coventry common stock at the time the merger is completed, you will be entitled to receive $2,730.00 in cash, without interest, and 38 Aetna common shares. In addition, you will be entitled to receive an amount of cash equal to 0.85 of an Aetna common share multiplied by the Aetna closing price.

The ratio of 0.3885 of an Aetna common share for each share of Coventry common stock (which is referred to in this 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 either Aetna or Coventry common stock changes. Therefore, the value of the stock portion of the merger consideration will depend on the market price of Aetna common shares at the time Coventry stockholders receive Aetna common shares in the merger. The market price of Aetna common shares has fluctuated since the date of the announcement of the merger agreement and will continue to fluctuate from the date of this proxy statement/prospectus to the date of the Coventry special meeting and the date the merger is completed and thereafter. The market price of Aetna common shares when received by Coventry stockholders after the merger is completed could be greater than, less than or the same as the market price of Aetna common shares on the date of this proxy statement/prospectus or at the time of the Coventry special meeting.

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

At completion of the merger, each option to purchase shares of Coventry common stock outstanding under any Coventry employee benefit plan, whether or not vested or exercisable, with a per share exercise price less than the sum of (a) $27.30 and (b) the product of (i) the Aetna closing price multiplied by (ii) the exchange ratio (which sum is referred to in this proxy statement/prospectus as the equity award cash consideration and which options are referred to in this proxy statement/prospectus as in-the-money options), will be cancelled and converted into the right to receive an amount in cash, without interest and less applicable withholding taxes, equal to the product of (x) the excess of (i) the equity award cash consideration over (ii) the applicable per share exercise price of that in-the-money option multiplied by (y) the total number of shares of Coventry common stock underlying that in-the-money option. During the 60-day period following the date of the merger agreement, Aetna, in consultation with Coventry, will consider the appropriate treatment of each option to purchase shares of Coventry common stock outstanding under any Coventry employee benefit plan, whether or not vested or exercisable, with a per share exercise price equal to or greater than the equity award cash consideration (which options are referred to in this proxy statement/prospectus as underwater options), taking into account the appropriate terms and conditions of each such option.

At completion of the merger, each outstanding restricted share of Coventry common stock (which represents a share of Coventry common stock subject to vesting and forfeiture restrictions) will be converted into the right to receive the merger consideration, less applicable withholding taxes.

At completion of the merger, each Coventry performance share unit and restricted stock unit outstanding under any Coventry employee benefit plan (which are collectively referred to in this proxy statement/prospectus as Coventry stock units) that, pursuant to its terms as of the date of the merger agreement, is vested or becomes vested upon completion of the merger (and each Coventry stock unit held by Allen F. Wise), which are collectively referred to in this proxy statement/prospectus as cashed-out units, will be converted into the right to receive an amount in cash, without interest and less applicable withholding taxes, equal to the product of (a) the equity award cash consideration multiplied by (b) the number of shares of Coventry common stock underlying that cashed-out unit.

At completion of the merger, each Coventry stock unit outstanding under any Coventry employee benefit plan that, pursuant to its terms as of the date of the merger agreement, is not vested and will not become vested upon completion of the merger (other than Coventry stock units held by Mr. Wise), which are referred to in this proxy statement/prospectus as rollover units, will be converted into a cash-settled Aetna restricted stock unit with the number of Aetna common shares underlying that cash-settled Aetna restricted stock unit equal to the product of (x) the number of shares of Coventry common stock underlying that rollover unit immediately prior to completion of the merger multiplied by (y) the quotient of (i) the equity award cash consideration divided by (ii) the Aetna closing price. Each such cash-settled Aetna restricted stock unit will be subject to the same terms and conditions (including service-based vesting) as applied to the corresponding rollover unit immediately prior to completion of the merger.

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

After careful consideration, Coventry’s board of directors unanimously determined that the merger agreement, the merger and the other transactions contemplated by the merger agreement are advisable for, fair to and in the best interests of Coventry and its stockholders and unanimously declared advisable and in all respects approved and adopted the merger agreement, the merger and the other transactions contemplated by the merger agreement. The Coventry board of directors unanimously recommends that Coventry stockholders vote “FOR” the adoption of the merger agreement. For the factors considered by the Coventry board of directors in reaching this decision, see “Proposal I: The Merger—Coventry Reasons for the Merger; Recommendation of the Coventry Board of Directors that Coventry Stockholders Adopt the Merger Agreement” beginning on page [—] of this proxy statement/prospectus.

The Coventry board of directors unanimously recommends that Coventry stockholders vote “FOR” the proposal to adjourn the Coventry special meeting if necessary to solicit additional proxies if there are not sufficient votes to adopt the merger agreement at the time of the Coventry special meeting. See “Proposal II: Adjournment of the Coventry Special Meeting” beginning on page [—] of this proxy statement/prospectus.

In addition, the Coventry board of directors unanimously recommends that Coventry stockholders vote “FOR” the proposal to approve, on an advisory (non-binding) basis, “golden parachute” compensation payments that will or may be paid by Coventry to its named executive officers in connection with the merger. See “Proposal III: Advisory Vote On Golden Parachute Compensation” beginning on page [—] of this proxy statement/prospectus.

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

The Coventry board of directors received an opinion from Greenhill & Co., LLC, which is referred to in this proxy statement/prospectus as Greenhill, that, as of August 19, 2012, and based on and subject to the qualifications, limitations and assumptions set forth in that opinion, the merger consideration to be received by the holders of shares of Coventry common stock pursuant to the merger agreement was fair, from a financial point of view, to such holders. The full text of Greenhill’s written opinion, dated August 19, 2012, which sets forth, among other things, the procedures followed, assumptions made, matters considered and qualifications and limitations on the scope of review undertaken by Greenhill in rendering its opinion, is attached as Annex B to this proxy statement/prospectus. The opinion was directed to the Coventry board of directors and addresses only the fairness, from a financial point of view, of the merger consideration to be received by the holders of shares of Coventry common stock entitled to receive such consideration. The opinion does not address any other aspect or implication of the merger and does not constitute a recommendation to the Coventry board of directors or to any other person in respect of the proposed merger, including as to how any holder of shares of Coventry common stock should vote or act in respect of the merger.

Ownership of Aetna After the Merger (See Page [—])

Based on the number of shares of Coventry common stock (including restricted shares) outstanding as of September 14, 2012, Aetna expects to issue approximately 52,014,586 Aetna common shares to Coventry stockholders pursuant to the merger. The actual number of Aetna common shares to be issued pursuant to the merger will be determined at completion of the merger based on the exchange ratio of 0.3885 and the number of shares of Coventry common stock (including restricted shares) outstanding at that time. Based on the number of shares of Coventry common stock (including restricted shares) outstanding as of September 14, 2012, and the number of Aetna common shares outstanding as of September 14, 2012, it is expected that, immediately after completion of the merger, former Coventry stockholders will own approximately 13.5% of the outstanding Aetna common shares.

Aetna Shareholder Approval Is Not Required

Aetna shareholders are not required to adopt the merger agreement or approve the merger or the issuance of the Aetna common shares in connection with the merger.

Interests of Certain Persons in the Merger (See Page [—])

In considering the recommendation of the Coventry board of directors to adopt the merger agreement, Coventry stockholders should be aware that Coventry’s directors and executive officers have interests in the merger that may be different from, or in addition to, the interests of Coventry stockholders generally. The Coventry board of directors was aware of these interests and considered them, among other matters, in evaluating and negotiating the merger agreement, in reaching its decision to approve the merger agreement and in recommending to the stockholders that the merger agreement be adopted.

These interests and arrangements include:

Listing of Aetna Common Shares and Delisting and Deregistration of Coventry Common Stock (See Page [—])

Aetna will apply to have the Aetna common shares to be issued in the merger approved for listing on the New York Stock Exchange, where Aetna common shares are currently traded. If the merger is completed, Coventry shares will no longer be listed on the New York Stock Exchange and will be deregistered under the Securities Exchange Act of 1934, as amended, which is referred to in this proxy statement/prospectus as the Exchange Act.

Appraisal Rights Available (See Page [—])

Under Delaware law, if the merger is completed, record holders of Coventry common stock who do not vote in favor of the adoption of the merger agreement and who otherwise properly assert their appraisal rights will be entitled to seek appraisal for, and obtain payment in cash for the judicially determined fair value of, their shares of Coventry common stock, in lieu of receiving the merger consideration. This value could be more than, the same as, or less than the value of the merger consideration. The relevant provisions of the General Corporation Law of the State of Delaware (which is referred to in this proxy statement/prospectus as the DGCL) are included as Annex C to this proxy statement/prospectus. You are encouraged to read these provisions carefully and in their entirety. Moreover, due to the complexity of the procedures for exercising the right to seek appraisal, Coventry stockholders who are considering exercising that right are encouraged to seek the advice of legal counsel. Failure to comply strictly with these provisions will result in loss of the right of appraisal.

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

As more fully described in this proxy statement/prospectus and in the merger agreement, the obligation of each of Aetna and Merger Sub, on the one hand, and Coventry, on the other hand, to complete the merger is subject to the satisfaction (or, to the extent permitted by applicable law, waiver) of a number of conditions, including the following:

In addition, the obligations of Aetna and Merger Sub to complete the merger are subject to the satisfaction (or, to the extent permitted by applicable law, waiver) of certain additional conditions, including (i) expiration or early termination of the waiting period relating to the merger under the Hart-Scott-Rodino Antitrust Improvements Act of 1976, as amended, and the rules and regulations thereunder, which is referred to in this proxy statement/prospectus as the HSR Act, and (ii) certain actions by or in respect of, and filings with, certain governmental authorities, which are referred to in this proxy statement/prospectus as the required governmental authorizations, having been made or obtained and being in full force and effect, without the imposition of any term or condition that would have or would reasonably be expected to have, individually or in the aggregate, a regulatory material adverse effect on Aetna or Coventry (see “The Merger Agreement—Reasonable Best Efforts Covenant” beginning on page [—] of this proxy statement/prospectus for a definition of regulatory material adverse effect).

In addition, the obligation of Coventry to complete the merger is subject to the satisfaction (or, to the extent permitted by applicable law, waiver) of certain additional conditions, including (i) expiration or early termination of the waiting period relating to the merger under the HSR Act and (ii) the required governmental authorizations having been made or obtained and being in full force and effect.

Aetna and Coventry 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 expiration or early termination of the waiting period relating to the merger under the HSR Act and the required governmental authorizations having been made or obtained and being in full force and effect.

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 proxy statement/prospectus as the FTC, and the Antitrust Division of the Department of Justice, which is referred to in this 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 early termination of that waiting period. If the DOJ or the FTC 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. Aetna and Coventry each filed its required HSR Act notification and report with respect to the merger on September 5, 2012. The waiting period under the HSR Act will expire on October 5, 2012, unless it is extended by a request for additional information or terminated earlier.

Pursuant to the insurance laws and regulations and, in some instances, the healthcare laws and regulations of certain states, and pursuant to certain licenses and contracts of certain of Coventry’s subsidiaries, applicable state regulatory authorities must approve, or be notified of, Aetna’s acquisition of control of Coventry’s health maintenance organizations, insurance companies and other regulated entities. To obtain these approvals and provide such notices, Aetna, or the applicable Aetna subsidiary, and in some instances Coventry, or the applicable Coventry regulated entity, as the case may be, has filed or will file acquisition of control and material modification or similar statements, notices or applications, as required by the insurance and healthcare laws and regulations of each applicable state or the Coventry regulated entities’ licenses and contracts.

Neither Aetna nor Coventry is aware of any material governmental approvals or actions that are required for completion of the merger other than those described above. It is presently contemplated that if any such additional material governmental approvals or actions are required, those approvals or actions will be sought.

Aetna and Coventry have agreed to use their respective reasonable best efforts to obtain all regulatory approvals required to complete the merger, which reasonable best efforts may include contesting any proceeding brought by a governmental authority seeking to prohibit completion of the merger or seeking damages or to impose any terms or conditions in connection with the merger. Except as described in the preceding sentence, in using its reasonable best efforts, under the terms of the merger agreement, Aetna is required to take all actions and do all things necessary, proper or advisable to complete the merger in connection with (i) the expiration or early termination of the waiting period relating to the merger under the HSR Act, (ii) any other antitrust law or (iii) the required governmental authorizations, except that Aetna is not required to take any action or agree to any term or condition in connection with those matters if that action, term or condition would have or would reasonably be expected to have, individually or in the aggregate, a regulatory material adverse effect on Aetna or on Coventry. In addition, in connection with obtaining the regulatory approvals required to complete the merger, (x) neither Aetna nor Coventry is required to take any action or agree to any term or condition that is not conditioned upon completion of the merger and (y) Coventry is not permitted to take any action or agree to any term or condition without Aetna’s consent.

Financing (See Page [—])

The merger agreement is not subject to a financing condition. On August 19, 2012, Aetna entered into a debt commitment letter with Goldman Sachs Bank USA, UBS Securities LLC and UBS Loan Finance LLC pursuant to which Goldman Sachs Bank USA and UBS Loan Finance LLC, which are referred to in this proxy statement/prospectus as the bridge lenders, have committed to provide up to $2.0 billion under a 364-day senior unsecured bridge loan to finance the cash consideration payable by Aetna in connection with the merger to the extent that Aetna has not received $2.0 billion of proceeds from the issuance of senior notes at or prior to completion of the merger. The bridge lenders’ commitment to provide the bridge loan is subject to several conditions as set forth in the debt commitment letter, including, among others, completion of the merger, the non-occurrence of a material adverse effect on Coventry, the negotiation of definitive bridge loan documentation, the accuracy of certain representations by Aetna, the absence of certain defaults by Aetna, Aetna having obtained public credit ratings of Aetna’s senior unsecured debt taking into account the merger, Aetna’s delivery of certain financial statements, Aetna having used commercially reasonable efforts to cause the senior notes to be issued and other customary conditions to completion. For a more complete description of Aetna’s debt financing for the merger, see “Proposal I: The Merger—Description of Debt Financing” beginning on page [—] of this proxy statement/prospectus.

The Merger Is Expected to be Completed in Mid-2013 (See Page [—])

The merger will occur within 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 proxy statement/prospectus, the merger is expected to be completed in mid-2013. However, there can be no assurance as to when, or if, the merger will occur.

No Solicitation by Coventry (See Page [—])

As more fully described in this proxy statement/prospectus and in the merger agreement, and subject to the exceptions described below, Coventry has agreed not to, among other things, (i) solicit, initiate or take any action to knowingly facilitate or knowingly encourage the submission of any competing acquisition proposal from any third party, (ii) enter into or participate in any discussions or negotiations with any third party that is seeking to make, or has made, a competing acquisition proposal or (iii) withdraw or modify in a manner adverse to Aetna the recommendation of the Coventry board of directors that Coventry stockholders adopt the merger agreement.

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

Coventry is only permitted to take the actions described above if Coventry’s board of directors determines that the failure to take that action would be reasonably likely to be inconsistent with its fiduciary duties to Coventry

stockholders under applicable law. In addition, Coventry is not permitted to withdraw or modify the recommendation of the Coventry board of directors that Coventry stockholders adopt the merger agreement (or terminate the merger agreement to enter into a definitive agreement providing for a superior acquisition proposal) unless, before taking that action, Coventry notifies Aetna that it intends to take that action and, if requested by Aetna, negotiates in good faith with Aetna for certain periods of time regarding any proposal by Aetna to amend the terms of the merger agreement.

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

As more fully described in this 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:

Termination Fees (See Page [—])

As more fully described in this proxy statement/prospectus and in the merger agreement, and subject to the terms and conditions described in the merger agreement, Coventry has agreed to pay Aetna a termination fee of $167.5 million if the merger agreement is terminated under any of the following circumstances:

As more fully described in this proxy statement/prospectus and in the merger agreement, and subject to the terms and conditions described in the merger agreement, Aetna has agreed to pay Coventry a termination fee of $450.0 million if both (x) the merger agreement is terminated under any the following circumstances:

and (y) at the time of termination of the merger agreement, all of the conditions to Aetna’s and Merger Sub’s obligations to complete the merger are satisfied other than (i) the regulatory approvals condition and (ii) the condition requiring the absence of any applicable law being in effect that prohibits completion of the merger (but only if that condition is not satisfied solely due to a final and non-appealable order in respect of certain regulatory matters).

Except in the case of fraud, if either party receives a termination fee in accordance with the provisions of the merger agreement, the receipt of the termination fee will be the receiving party’s sole and exclusive remedy against the paying party.

See “The Merger Agreement—Termination Fee and Expenses” beginning on page [—] of this proxy statement/prospectus for a more complete description of the circumstances under which Coventry or Aetna will be required to pay a termination fee.

Specific Performance; Remedies (See Page [—])

Under the merger agreement, each of Aetna and Coventry is entitled to seek 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 (See Page [—])

In general, U.S. holders (as defined under “Proposal I: The Merger—Material U.S. Federal Income Tax Consequences” beginning on page [—] of this proxy statement/prospectus) will recognize capital gain or loss for U.S. federal income tax purposes on the exchange of their Coventry common stock for Aetna common shares and cash in an amount equal to the difference, if any, between (i) the sum of the fair market value of the Aetna common shares on the date of the exchange and cash received (including cash received in lieu of a fractional Aetna common share) and (ii) the U.S. holder’s adjusted tax basis in the Coventry common stock surrendered in the exchange.

The U.S. federal income tax consequences described above may not apply to all holders of Coventry common stock, including certain holders specifically referred to on page [—] of this proxy statement/prospectus. Your tax consequences will depend on your own situation. You should consult your tax advisor to determine the particular tax consequences of the merger to you.

Accounting Treatment (See Page [—])

The merger will be accounted for as an acquisition of a business. Aetna will record assets acquired and liabilities assumed from Coventry primarily at their respective fair values at the date of completion of the merger. Any excess of the purchase price (as described under Note 4. Estimate of Consideration Expected to be Transferred under “Aetna And Coventry Unaudited Pro Forma Condensed Combined Financial Statements” beginning on page [—] of this proxy statement/prospectus) over the net fair value of such assets and liabilities will be recorded as goodwill.

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

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

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

On August 23, 2012, a putative stockholder class action lawsuit captioned Coyne v. Wise et al., C.A. No. 367380, was filed in the Circuit Court for Montgomery County, Maryland, against the Coventry board of directors, Coventry, Aetna and Merger Sub. On August 27, 2012, a second putative stockholder class action lawsuit captioned O’Brien v. Coventry Health Care, Inc. et al, C.A. 367577, was filed in the Circuit Court for

Montgomery County, Maryland, against the Coventry board of directors, Coventry, Aetna and Merger Sub. On September 5, 2012, a third putative stockholder class action lawsuit captioned Preze v. Coventry Health Care, Inc. et al., C.A. 367942, was filed in the Circuit Court for Montgomery County, Maryland, against the Coventry board of directors, Coventry, Aetna and Merger Sub. The complaints in all three lawsuits generally allege, among other things, that the individual defendants breached their fiduciary duties owed to public stockholders of Coventry in connection with the merger because the merger consideration and certain other terms in the merger agreement are unfair. The complaints further allege that Aetna and Merger Sub aided and abetted these alleged breaches of fiduciary duty. In addition, the complaints generally allege that the proposed merger improperly favors Aetna and that certain provisions of the merger agreement unduly restrict Coventry’s ability to negotiate with other potential bidders. Among other remedies, the complaints generally seek injunctive relief prohibiting the defendants from completing the proposed merger or, in the event that an injunction is not awarded, unspecified money damages, costs and attorneys’ fees.

On August 31, 2012, a putative stockholder class action lawsuit captioned Brennan v. Coventry Health Care, Inc. et al., C.A. No. 7826-CS, was filed in the Court of Chancery of the State of Delaware against the Coventry board of directors, Coventry, Aetna and Merger Sub. On September 14, 2012, a second putative stockholder class action lawsuit captioned Nashelsky v. Coventry Health Care, Inc. et al., C.A. No. 7868-CS, was filed in the Court of Chancery of the State of Delaware against the Coventry board of directors, Coventry, Aetna and Merger Sub. The complaints generally allege that, among other things, the individual defendants breached their fiduciary duties owed to the public stockholders of Coventry in connection with the merger because the merger consideration and certain other terms in the merger agreement are unfair. The complaints further allege that Aetna and Merger Sub aided and abetted these alleged breaches of fiduciary duty. In addition, the complaints generally allege that certain provisions of the merger agreement unduly restrict Coventry’s ability to negotiate with other potential bidders and that the merger agreement lacks adequate safeguards on behalf of Coventry’s stockholders against the decline in the value of the stock component of the merger consideration. Among other remedies, the complaints generally seek injunctive relief prohibiting the defendants from completing the proposed merger, rescissionary and other types of damages and costs and attorneys’ fees.

SELECTED HISTORICAL CONSOLIDATED FINANCIAL DATA OF AETNA

The following table presents selected historical consolidated financial data of Aetna. The selected financial data of Aetna for each of the years ended December 31, 2011, 2010 and 2009, and as of December 31, 2011 and 2010, are derived from Aetna’s audited consolidated financial statements and related notes contained in its Annual Report on Form 10-K for the year ended December 31, 2011, which is incorporated by reference into this proxy statement/prospectus. The selected financial data of Aetna for each of the years ended December 31, 2008 and 2007, and as of December 31, 2009, 2008 and 2007, have been derived from Aetna’s audited consolidated financial statements for such years, which have not been incorporated by reference into this proxy statement/prospectus. The selected financial data of Aetna as of, and for the six months ended, June 30, 2012, are derived from Aetna’s unaudited consolidated financial statements and related notes contained in its Quarterly Report on Form 10-Q for the quarterly period ended June 30, 2012, which is incorporated by reference into this proxy statement/prospectus. The selected financial data of Aetna as of, and for the six months ended, June 30, 2011, are derived from Aetna’s unaudited consolidated financial statements and related notes contained in its Quarterly Report on Form 10-Q for the quarterly period ended June 30, 2011, which has not been incorporated by reference into this proxy statement/prospectus. Aetna’s management believes that Aetna’s interim unaudited financial statements have been prepared on a basis consistent with its audited financial statements and include all normal and recurring adjustments necessary for a fair presentation of the results for each interim period.

SELECTED HISTORICAL CONSOLIDATED FINANCIAL DATA OF COVENTRY

The following table presents selected historical consolidated financial data of Coventry. The selected financial data of Coventry for each of the years ended December 31, 2011, 2010 and 2009, and as of December 31, 2011 and 2010, are derived from Coventry’s audited consolidated financial statements and related notes contained in its Annual Report on Form 10-K for the year ended December 31, 2011, which is incorporated by reference into this proxy statement/prospectus. The selected financial data of Coventry for each of the years ended December 31, 2008 and 2007, and as of December 31, 2009, 2008 and 2007, have been derived from Coventry’s audited consolidated financial statements for such years, which have not been incorporated by reference into this proxy statement/prospectus. The selected financial data of Coventry as of, and for the six months ended, June 30, 2012, are derived from Coventry’s unaudited consolidated financial statements and related notes contained in its Quarterly Report on Form 10-Q for the quarterly period ended June 30, 2012, which is incorporated by reference into this proxy statement/prospectus. The selected financial data of Coventry as of, and for the six months ended, June 30, 2011, are derived from Coventry’s unaudited consolidated financial statements and related notes contained in its Quarterly Report on Form 10-Q for the quarterly period ended June 30, 2011, which has not been incorporated by reference into this proxy statement/prospectus. Coventry’s management believes that Coventry’s interim unaudited financial statements have been prepared on a basis consistent with its audited financial statements and include all normal and recurring adjustments necessary for a fair presentation of the results for each interim period.