Q   ANNUAL REPORT PURSUANT TO SECTION 13 OR 15(d) OF

For the fiscal year ended December 31, 2011

o  TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF

For the transition period from                      to                     

Indicate by check mark if the registrant is a well-known seasoned issuer, as defined in Rule 405 of the Act. Yes Q No o

Indicate by check mark if the registrant is not required to file reports pursuant to Section 13 or Section 15(d) of the Act. Yes o No Q

Indicate by check mark whether the registrant (1) has filed all reports required to be filed by Section 13 or 15(d) of the Securities Exchange Act of 1934 during the preceding 12 months (or for such shorter period that the registrant was required to file such reports), and (2) has been subject to such filing requirements for the past 90 days. Yes Q  No o

Indicate by check mark whether the registrant has submitted electronically and posted on its corporate Web site, if any, every Interactive Data File required to be submitted and posted pursuant to Rule 405 of Regulation S-T (§232.405 of this chapter) during the preceding 12 months (or for such shorter period that the registrant was required to submit and post such files). Yes Q  No o

Indicate by check mark if disclosure of delinquent filers pursuant to Item 405 of Regulation S-K (§229.405 of this chapter) is not contained herein, and will not be contained, to the best of registrant’s knowledge, in definitive proxy or information statements incorporated by reference in Part III of this Form 10-K or any amendment to this Form 10-K. o

Indicate by check mark whether the registrant is a large accelerated filer, an accelerated filer, a non-accelerated filer, or a smaller reporting company, as defined in Rule 12b-2 of the Act. Large accelerated filer Q, Accelerated filer o, Non-accelerated filer o, Smaller reporting company o

Indicate by check mark whether the registrant is a shell company (as defined in Rule 12b-2 of the Act). Yes o  No Q

The aggregate market value of Common Shares held by nonaffiliates of the registrant at June 30, 2011 was $3,347.1 million based on the closing sale price of the Common Shares on the New York Stock Exchange on that date.

The number of Common Shares outstanding at February 15, 2012 was 51,499,959.

The information required by Part III of this report, to the extent not set forth herein, is incorporated by reference to the registrant’s Definitive Proxy Statement to be filed in respect of our 2012 Annual General Meeting of Shareholders.

RenaissanceRe was established in Bermuda in 1993 to write principally property catastrophe reinsurance and today is a leading global provider of reinsurance and insurance coverages and related services. Our aspiration is to be the world’s best underwriter of high-severity, low frequency risks. Through our operating subsidiaries, we seek to produce superior returns for our shareholders by being a trusted, long-term partner to our customers, for assessing and managing risk, delivering responsive solutions, and keeping our promises. We accomplish this by leveraging our core capabilities of risk assessment and information management, and by investing in our capabilities to serve our customers across the cycles that have historically characterized our markets. Overall, our strategy focuses on superior risk selection, customer relationships and capital management. We provide value to our customers and joint venture partners in the form of financial security, innovative products, and responsive service. We are known as a leader in paying valid reinsurance claims promptly. We principally measure our financial success through long-term growth in tangible book value per common share plus the change in accumulated dividends, which we believe is the most appropriate measure of our Company’s financial performance, and believe we have delivered superior performance in respect of this measure over time.

For the year ended December 31, 2011, our Reinsurance, Lloyd’s and Insurance segments accounted for 92.2%, 7.8% and 0.0%, respectively, of our total consolidated gross premiums written. We currently expect contributions from our Lloyd’s segment to increase over time, on both an absolute and relative basis, although we cannot assure you we will succeed in meeting this goal. Financial data relating to our segments is included in “Item 7. Management’s Discussion and Analysis of Financial Condition and Results of Operations.”

Our portfolio of business has continued to be increasingly characterized by relatively large transactions with ceding companies with whom we do business, although no current relationship exceeds 10% of our gross premiums written. Accordingly, our gross premiums written are subject to significant fluctuations depending on our success in maintaining or expanding our relationships with these large customers. We market our reinsurance products worldwide exclusively through brokers, whose market has become extremely consolidated in recent years.  In 2011, three brokerage firms accounted for 90.7% of our Reinsurance

The following table shows our total Reinsurance segment gross premiums written split between catastrophe and specialty reinsurance, respectively:

Catastrophe Excess of Loss Reinsurance.  We principally write catastrophe reinsurance on an excess of loss basis, which means we provide coverage to our insureds when aggregate claims and claim expenses from a single occurrence of a covered peril exceed the attachment point specified in a particular contract. Under these contracts, we indemnify an insurer for a portion of the losses on insurance policies in excess of a specified loss amount, and up to an amount per loss specified in the contract. The coverage provided under excess of loss reinsurance contracts may be on a worldwide basis or limited in scope to selected geographic areas. Coverage can also vary from “all property” perils to limited coverage on selected perils, such as “earthquake only” coverage.

Excess of Loss Retrocessional Reinsurance.  We also write retrocessional reinsurance contracts that provide property catastrophe coverage to other reinsurers or retrocedants. In providing retrocessional reinsurance, we focus on property catastrophe retrocessional reinsurance, which covers the retrocedant on an excess of loss basis when aggregate claims and claim expenses from a single occurrence of a covered peril and from a multiple number of reinsureds exceed a specified attachment point. The coverage provided under excess of loss retrocessional contracts may be on a worldwide basis or limited in scope to selected geographic areas. Coverage can also vary from “all property” perils to limited coverage on selected perils, such as “earthquake only” coverage. The information available to retrocessional underwriters concerning the original primary risk can be less precise than the information received from primary companies directly. Moreover, exposures from retrocessional business can change within a contract term as the underwriters of a retrocedant alter their book of business after retrocessional coverage has been bound.

Insurance-Linked Securities.  We also invest in insurance-linked securities. Insurance-linked securities are generally privately placed fixed income securities as to which all or a portion of the repayment of the principal is linked to catastrophic events; for example, the occurrence of one or more hurricanes or earthquakes producing industry losses exceeding certain specified thresholds. We underwrite, model, evaluate and monitor these securities using similar tools and techniques used to evaluate our more traditional property catastrophe reinsurance business assumed. In addition, we may enter into derivative transactions, such as total return swaps, that are based on or referenced to underlying insurance-linked securities. Based on an evaluation of the specific features of each insurance-linked security, we account for these securities as reinsurance or at fair value, as applicable, in accordance with U.S. generally accepted accounting principles (“GAAP”). In addition, in future periods we may utilize the growing market for insurance-linked securities to expand our ceded reinsurance buying if we find the pricing and terms of such coverage attractive.

Property Catastrophe Managed Joint Ventures.  We actively manage property catastrophe-oriented joint ventures, which provide us with an additional presence in the market, enhance our client relationships and generate fee income and profit commissions. These joint ventures allow us to leverage our access to business and our underwriting capabilities on a larger capital base. Currently, our joint ventures include Top Layer Re and DaVinci. Renaissance Underwriting Managers, Ltd. (“RUM”), a wholly owned subsidiary of the Company, acts as the exclusive underwriting manager for each of these joint ventures.

DaVinci was established in 2001 and principally writes property catastrophe reinsurance and certain low frequency, high severity specialty reinsurance lines of business on a global basis. In general, we seek to construct for DaVinci a property catastrophe reinsurance portfolio with risk characteristics similar to those of Renaissance Reinsurance’s property catastrophe reinsurance portfolio and certain lines of specialty reinsurance such as terrorism and catastrophe exposed workers’ compensation. In accordance with DaVinci’s underwriting guidelines, it can only participate in business that is underwritten by Renaissance Reinsurance. We maintain majority voting control of DaVinciRe and, accordingly, consolidate the results of DaVinciRe into our consolidated results of operations and financial position. We seek to manage DaVinci’s capital efficiently over time in light of the market opportunities and needs we perceive and believe we are able to serve. Our ownership in DaVinciRe was 42.8% and 41.2% at December 31, 2011 and 2010, respectively. Effective January 1, 2012, we sold a portion of our shares of DaVinciRe to a new third party shareholder, and subsequent to the transaction, our ownership interest in DaVinciRe decreased to 34.7%. We expect our ownership in DaVinciRe to fluctuate over time. See "Item 7. Management's Discussion and Analysis of Financial Condition and Results of Operations, Capital Resources" for additional information with respect of DaVinci.

Weather and Energy Risk Management Operations.  We provide weather and energy related risk management solutions and financial products primarily through Renaissance Trading and REAL and sell certain financial products primarily to address weather risks, and engage in certain weather, energy and commodity derivatives trading activities. Certain of these trading activities require the physical delivery of energy-related commodities, including natural gas. We expect that our participation will increase in the trading markets for securities and derivatives linked to energy, commodities, weather, other natural phenomena, and/or products or indices linked in part to such phenomena. While our activities focus on financial products that allow various energy, utility and other customers to manage their exposures to energy related commodities, we expect our own results in this area to potentially be volatile over time. As this unit grows, we intend to seek to continue to invest in operating and control environment systems and procedures, hire staff and develop and install management information and other systems. Accordingly, costs related to these operational investments have increased and may increase in the future. We continue to allocate an increasing amount of capital to our weather and energy risk management operations, and have offered certain new financial products within this group. We also continually seek new markets and relationships for our weather and energy risk products, including leveraging strategic affiliations and ceding risk where appropriate.  Although there can be no assurances, it is possible that our results from these activities will increase on an absolute or relative basis over time.

Strategic Investments.  Ventures also pursues strategic investments where, rather than assuming exclusive management responsibilities ourselves, we instead partner with other market participants. These investments are directed at classes of risk other than catastrophe, and at times may also be directed at non-insurance risks. We find these investments attractive both for their expected returns, and also because they provide us diversification benefits and information and exposure to other aspects of the market. Examples of these investments include our investments in Tower Hill Insurance Group, LLC. (“THIG”), Tower Hill Holdings, Inc. ("Tower Hill") and Tower Hill Signature Insurance Holdings, Inc. ("Tower Hill Signature"), (collectively, the “Tower Hill Companies”), Angus Partners, LLC. ("Angus"), Angus Fund L.P. (the “Angus Fund”) and Essent Group Ltd. (“Essent”). THIG is a managing general agency specializing in

Controls and Compliance Committee.  We believe that a key component of our current operational risk management platform is our Controls and Compliance Committee. The Controls and Compliance Committee is comprised of our CFO, CCO, CAO, Chief Administrative Officer, CRO, staff compliance professionals and representatives from our business units. The purpose of the Controls and Compliance Committee is to establish, assess the effectiveness of, and enforce policies, procedures and practices relating to accounting, financial reporting, internal controls, regulatory, legal, compliance and related matters, for ensuring compliance with applicable laws and regulations, the Company’s Code of Ethics and Conduct (the “Code of Ethics”), and other relevant standards. In addition, the Controls and Compliance Committee is charged with reviewing certain transactions that potentially raise complex and/or significant tax, legal, accounting, regulatory, financial reporting, reputational or compliance issues.

Ongoing Development and Enhancement.  We seek to reflect and categorize risks we monitor in part through quantitative risk distributions, even where we believe that such quantitative analysis is not as robust or well developed as our tools and models for measuring and evaluating other risks, such as catastrophe and market risks. We also seek to improve the methods by which we measure risks. We believe effective risk management is a core attribute of our culture and is a continual process that requires ongoing improvement and development. We seek from time to time to identify new best practices or additional developments both from within our industry and from other sectors. We believe that our ongoing efforts to embed ERM throughout our organization are important to our efforts to produce and maintain a competitive advantage to achieve our corporate goals.

Our exposures are generally diversified across geographic zones, but are also a function of market conditions and opportunities. Our largest exposure has historically been to the U.S. and Caribbean property catastrophe market, which represented 61.7% of the Company’s gross premiums written for the year ended December 31, 2011. A significant amount of our U.S. and Caribbean premium provides coverage against windstorms, mainly U.S. Atlantic hurricanes, as well as earthquakes and other natural and man-made catastrophes. The following table sets forth the percentage of our gross premiums written allocated to the territory of coverage exposure:

The following table summarizes our claims and claim expense reserves by line of business and split between case reserves, additional case reserves and IBNR at December 31, 2011 and 2010:

Our estimates of claims and claim expense reserves are not precise in that, among other matters, they are based on predictions of future developments and estimates of future trends and other variable factors. Some, but not all, of our reserves are further subject to the uncertainty inherent in actuarial methodologies and estimates. Because a reserve estimate is simply an insurer’s estimate at a point in time of its ultimate liability, and because there are numerous factors which affect reserves and claims payments that cannot be determined with certainty in advance, our ultimate payments will vary, perhaps materially, from our estimates of reserves. If we determine in a subsequent period that adjustments to our previously established reserves are appropriate, such adjustments are recorded in the period in which they are identified. During the year ended December 31, 2011, changes to prior year estimated claims reserves decreased our net loss by $132.0 million (2010 - increased our net income by $302.1 million, 2009 - increased our net income by $266.2 million), excluding the consideration of changes in reinstatement premium, profit commissions, redeemable noncontrolling interest - DaVinciRe, equity in net claims and claim expenses of Top Layer Re and income tax.

The following table represents the development of our GAAP balance sheet reserves for December 31, 2001 through December 31, 2011. This table does not present accident or policy year development data. The top line of the table shows the gross reserves for claims and claim expenses at the balance sheet date for each of the indicated years. This represents the estimated amounts of claims and claim expenses arising in the current year and all prior years that are unpaid at the balance sheet date, including additional case reserves and IBNR reserves. The table also shows the re-estimated amount of the previously recorded reserves based on experience as of the end of each succeeding year. The estimate changes as more information becomes known about the frequency and severity of claims for individual years. The “cumulative redundancy on net reserves” represents the aggregate change to date from the indicated estimate of the gross reserve for claims and claim expenses, net of reinsurance recoverable on the second line of the table. The table also shows the cumulative net paid amounts as of successive years with respect to the net reserve liability. At the bottom of the table is a reconciliation of the gross reserve for claims and claim expenses to the net reserve for claims and claim expenses, the gross re-estimated liability to the net re-estimated liability for claims and claim expenses, and the cumulative redundancy on gross reserves.