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

For the fiscal year ended December 31, 2012

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, 2012 was $3,558.0 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, par value US $1.00 per share, outstanding at February 20, 2013 was 44,218,306.

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 2013 Annual General Meeting of Shareholders.

As described in more detail below under "Segments", our reportable segments currently include: (1) Reinsurance, which includes catastrophe reinsurance, specialty reinsurance and certain property catastrophe and specialty joint ventures and (2) Lloyd's, which includes reinsurance and insurance business written through Syndicate 1458. As of December 31, 2012, we undertook a review of our reportable segments and concluded that our former Insurance segment no longer met the quantitative thresholds defined in Financial Accounting Standards Board ("FASB") Accounting Standards Codification ("ASC") Topic Segment Reporting. These operations are not actively involved in pursuing business opportunities and are in run-off; therefore we determined they no longer require, nor warrant, separate disclosure as a reportable segment. As such, the results of operations of the former Insurance segment have been included in our Other category as noted below, and all prior periods presented herein have been reclassified to conform with the current year presentation. Our Other category primarily reflects our: strategic investments; weather and energy risk management operations; investments unit; corporate expenses, capital servicing costs and noncontrolling interests; results of our discontinued operations; and now, in addition, the remnants of our Bermuda-based insurance operations not sold pursuant to the Stock Purchase Agreement, as defined herein, with QBE Holdings, Inc. ("QBE").

Superior Risk Selection.  We seek to build a portfolio of risks that produces an attractive return on utilized capital.  We develop a perspective of the risk in each business opportunity using both our underwriters' expertise and sophisticated risk selection techniques including computer models and databases, such as Renaissance Exposure Management System ("REMS©").  We pursue a disciplined approach to underwriting and select only those risks that we believe will produce a portfolio with an attractive return,

Superior Customer Relationships.  We believe our modeling and technical expertise, and the risk management products that we provide our customers, has enabled us to become a provider of first choice in many lines of business to our customers worldwide.  We seek to offer stable, predictable, and consistent risk-based pricing and a prompt turnaround on our claims.

Superior Capital Management.  We seek to write as much attractively priced business as is available to us and then manage our capital accordingly.  We generally seek to raise capital when we forecast an increased demand in the market, at times by accessing capital through joint ventures or other structures, and seek to return capital to our shareholders or joint venture investors when the demand for our coverages appears to decline and when we believe a return of capital would be beneficial to our shareholders or joint venture investors.  In using joint ventures, we intend to leverage our access to business and our underwriting capabilities on an efficient capital base, develop fee income, generate profit commissions and diversify our portfolio. We routinely evaluate and review potential joint venture opportunities and strategic investments.

As discussed above, our reportable segments currently include: (1) Reinsurance, which includes catastrophe reinsurance, specialty reinsurance and certain property catastrophe and specialty joint ventures and (2) Lloyd's, which includes reinsurance and insurance business written through Syndicate 1458. In addition, our Other category primarily reflects our: strategic investments; weather and energy risk management operations; investments unit; corporate expenses, capital servicing costs and noncontrolling interests; results of our discontinued operations; and now, in addition, the remnants of our Bermuda-based insurance operations not sold pursuant to the Stock Purchase Agreement with QBE.

For the year ended December 31, 2012, our Reinsurance and Lloyd's segment accounted for 89.8% and 10.2%, 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. Operating results 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 2012, three brokerage firms accounted for 84.6% of our Reinsurance segment gross premiums written.  We believe that recent market dynamics, and trends in our industry in respect of potential future consolidation, have increased our exposure to the risks of broker, client and counterparty concentration.

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 all or a specified portion of the losses on underlying insurance policies in excess of a specified 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

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 principal 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.

construct for DaVinci a property catastrophe reinsurance portfolio with risk characteristics similar to those of Renaissance Reinsurance's property catastrophe reinsurance portfolio and a portfolio of 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 30.8% at December 31, 2012 (2011 - 42.8%). During January 2013 DaVinciRe redeemed shares from certain DaVinciRe shareholders, including us, while certain other existing DaVinciRe shareholders purchased additional shares in DaVinciRe. Subsequent to the above transactions, our ownership in DaVinciRe increased to 32.9% effective January 1, 2013.

Effective January 1, 2012, we formed and launched a managed joint venture, Upsilon Reinsurance Ltd. ("Upsilon Re"), a Bermuda domiciled special purpose insurer ("SPI"), to provide additional capacity to the worldwide aggregate and per-occurrence retrocessional property catastrophe excess of loss market for the 2012 underwriting year. The original business was written by ROE, a wholly owned subsidiary of RenaissanceRe, and included $37.4 million of gross premiums written incepting between January 1, 2012 and June 1, 2012. A portion of this business was in turn ceded to Upsilon Re under a fully-collateralized retrocessional reinsurance contract, effective January 1, 2012. In conjunction with the formation and launch of Upsilon Re, $16.8 million of non-voting Class B shares were sold to external investors, and we invested $48.8 million in Upsilon Re's non-voting Class B shares, representing a 74.5% ownership interest in Upsilon Re. The Class B shareholders participate in substantially all of the profits or losses of Upsilon Re while the Class B shares remain outstanding. The holders of Class B shares indemnify Upsilon Re against losses relating to insurance risk. In addition, another third party investor supplied $17.6 million of capital through a reinsurance participation (a third party quota share agreement) with ROE alongside Upsilon Re. Inclusive of the reinsurance participation, we have a 61.4% participation in the original risks assumed by ROE related to Upsilon Re. During February 2013, Upsilon Re redeemed a portion of its outstanding third party non-voting Class B shares for $20.5 million as a result of the scheduled expiration of certain risks underwritten by Upsilon Re, subject to a holdback for development of claims and claim expenses.  Following the redemption, third-party non-voting Class B Shares with a GAAP book value of $2.2 million as at December 31, 2012, remained outstanding.  In addition, the Company has authorized the release of $21.9 million of collateral to a third party investor who participated in risks underwritten by ROE related to Upsilon Re through a reinsurance participation. Both Upsilon Re and the reinsurance participation are managed by RUM in return for an expense override, as well as a potential underwriting profit commission. Upsilon Re is considered a variable interest entity ("VIE") and we are considered the primary beneficiary. As a result, Upsilon Re is consolidated by the Company and all significant inter-company transactions have been eliminated.

Effective June 1, 2012, we formed and launched a managed joint venture, Timicuan Reinsurance III Limited ("Tim Re III"), a Bermuda domiciled SPI, to provide collateralized reinsurance in respect of a portfolio of Florida reinstatement premium protection ("RPP") contracts. The original business was written by Renaissance Reinsurance and DaVinci, and included $41.1 million of gross premiums written incepting June 1, 2012, of which Renaissance Reinsurance and DaVinci ceded $37.7 million to Tim Re III under a fully-collateralized reinsurance contract. In conjunction with the formation and launch of Tim Re III, $44.8 million of Tim Re III's non-voting Class B shares were sold to external investors. Additionally, $10.3 million of the non-voting Class B shares were acquired by us, representing an 18.6% ownership interest in Tim Re III. The Class B shareholders participate in substantially all of the profits or losses of Tim Re III while the

Class B shares remain outstanding. The holders of Class B shares indemnify Tim Re III against losses relating to insurance risk. In addition, another third party investor supplied $5.2 million of capital through a reinsurance participation with Renaissance Reinsurance and DaVinci, alongside Tim Re III. Inclusive of the reinsurance participation, we have a 17.1% participation in the original risks assumed by Renaissance Reinsurance and DaVinci related to Tim Re III. Both Tim Re III and the reinsurance participation are managed by RUM in return for a potential underwriting profit commission. Tim Re III is considered a VIE and we are considered the primary beneficiary. As a result, Tim Re III is consolidated by the Company and all significant inter-company transactions have been eliminated.

Effective January 1, 2013, we formed and launched a managed joint venture, Upsilon Reinsurance II Ltd. ("Upsilon Re II"), a Bermuda domiciled SPI, to provide additional capacity to the worldwide aggregate and per-occurrence retrocessional property catastrophe excess of loss market for the 2013 underwriting year. Original business was written directly by Upsilon Re II and included $53.5 million of gross premiums written incepting January 1, 2013 under fully-collateralized reinsurance contracts. In conjunction with the formation and launch of Upsilon Re II, $61.0 million of Upsilon Re II non-voting Class B shares were sold to external investors. Additionally, $76.4 million of the non-voting Class B shares were acquired by us, representing a 55.6% ownership interest in Upsilon Re II. The Class B shareholders participate in substantially all of the profits or losses of Upsilon Re II while the Class B shares remain outstanding. The holders of Class B shares indemnify Upsilon Re II against losses relating to insurance risk. In addition, another third party investor supplied $17.5 million of capital through an insurance contract with the Company related to Upsilon Re II's reinsurance portfolio. Inclusive of the insurance contract, we have a 42.9% participation in the original risks assumed by Upsilon Re II. Both Upsilon Re II and the insurance contract are managed by RUM in return for an expense override, as well as a potential underwriting profit commission. Upsilon Re II is considered a VIE and we are considered the primary beneficiary. As a result, Upsilon Re II will be consolidated by the Company and all significant inter-company transactions will be eliminated.

Weather and Energy Risk Management Operations.  We provide weather and energy related risk management solutions and financial products primarily through Renaissance Trading and REAL. Renaissance Trading sells financial products primarily to address weather risks, and engage in certain weather, energy and commodity derivatives trading activities, including trading securities and derivatives linked to energy, commodities, weather, other natural phenomena, and/or products or indices linked in part to such phenomena. Certain of these trading activities require the physical delivery of energy-related commodities, including natural gas. While our activities focus on 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 be volatile over time. We continually seek new markets and relationships for our weather and energy risk products, including continued leveraging of strategic affiliations and ceding risk through similar arrangements where we deem 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, or in respect of any other period. As with our reinsurance operations, we seek to obtain capital support, volatility protection and other enhancements to the capital we deploy in respect of this business. However, we cannot assure you we will succeed in these initiatives in the future, or in maintaining the capital support and other related transactions currently in effect.

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.

Business activities that appear in our consolidated underwriting results, such as DaVinci and certain reinsurance transactions, are included in our Reinsurance segment results; the results of our investments, such as Top Layer Re, our weather and energy related activities and other ventures are included in the Other category of our segment results.

Our Lloyd's segment includes insurance and reinsurance business written for our own account through Syndicate 1458. Syndicate 1458 commenced business by writing certain lines of insurance and reinsurance business incepting on or after June 1, 2009. The syndicate was established to enhance our underwriting platform by providing access to Lloyd's extensive distribution network and worldwide licenses. RenaissanceRe Corporate Capital (UK) Limited ("RenaissanceRe CCL"), an indirect wholly owned subsidiary of the Company, is the sole corporate member of Syndicate 1458. RenaissanceRe Syndicate Management Ltd. ("RSML"), a wholly owned subsidiary of RenaissanceRe, is the managing agent for Syndicate 1458. We anticipate that Syndicate 1458's absolute and relative contributions to our consolidated results of operations will have a meaningful impact over time, although we cannot assure you we will succeed in executing our growth strategy in respect of Syndicate 1458, or that its results will be favorable.

Our Other category primarily includes the results of: (1) our share of strategic investments in certain markets we believe offer attractive risk-adjusted returns or where we believe our investment adds value, and where, rather than assuming exclusive management responsibilities ourselves, we partner with other market participants; (2) our weather and energy risk management operations primarily through Renaissance Trading and REAL; (3) our investment unit which manages and invests the funds generated by our consolidated operations; (4) corporate expenses, capital services costs and noncontrolling interests; (5) the results of our discontinued operations; and (6) as described in more details above, the remnants of our Bermuda-based insurance operations not sold pursuant to the Stock Purchase Agreement with QBE.

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 63.4% of the Company's gross premiums written for the year ended December 31, 2012. 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:

We periodically review the estimates and assumptions that are reflected in REMS© and our other tools. For example, the 2011 and 2010 earthquake events in New Zealand and the Tohoku earthquake provided new insight on certain aspects of hazard and vulnerability to the global earthquake science community. Utilizing internal research capabilities from our team of scientists at Weather Predict Consulting Inc. ("Weather Predict") and new research from the global earthquake science community, we updated several of our internal regional representations of earthquake risk in advance of the commercially available models. In late 2012, storm Sandy gave rise to new data relating to storm surge, flood persistence and mid-Atlantic tropical storm meteorology.

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, and 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 effective new 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.

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

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, 2012, changes to prior year estimated claims reserves increased our net income by $158.0 million (2011 - decreased our net loss by $132.0 million, 2010 - increased our net income by $302.1 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 presents an analysis of our paid, unpaid and incurred losses and loss expenses and a reconciliation of beginning and ending reserves for claims and claim expenses for the years indicated:

Our estimates of losses from large events are based on factors including currently available information derived from the Company's claims information from certain customers and brokers, industry assessments of losses from the events, proprietary models, and the terms and conditions of our contracts. The uncertainty of our estimates for certain of these large events is additionally impacted by the preliminary nature of the information available, the magnitude and relative infrequency of the events, the expected duration of the respective claims development period, inadequacies in the data provided thus far by industry participants and the potential for further reporting lags or insufficiencies (particularly in respect of the Chilean, 2010 New Zealand, 2011 New Zealand and Tohoku earthquakes); and in the case of storm Sandy and the Thailand flooding, significant uncertainty as to the form of the claims and legal issues, under the relevant terms of insurance contracts and reinsurance treaties. In addition, a significant portion of the net claims and claim expenses associated with storm Sandy and the New Zealand and Tohoku earthquakes are concentrated with a few large clients and therefore the loss estimates for these events may vary significantly based on the claims experience of those clients. Loss reserve estimation in respect of our retrocessional contracts poses further challenges compared to directly assumed reinsurance. A significant

portion of our reinsurance recoverable relates to the New Zealand and Tohoku earthquakes. There is inherent uncertainty and complexity in evaluating loss reserve levels and reinsurance recoverable amounts, due to the nature of the losses relating to earthquake events, including that loss development time frames tend to take longer with respect to earthquake events. The contingent nature of business interruption and other exposures will also impact losses in a meaningful way, especially with regard to storm Sandy, the Tohoku earthquake and Thailand flooding, which we believe may give rise to significant complexity in respect of claims handling, claims adjustment and other coverage issues, over time. Given the magnitude and relatively recent occurrence of these large events, meaningful uncertainty remains regarding total covered losses for the insurance industry and, accordingly, several of the key assumptions underlying our loss estimates. In addition, our actual net losses from these events may increase if our reinsurers or other obligors fail to meet their obligations.

Our reserving techniques, assumptions and processes differ between our property catastrophe reinsurance, specialty reinsurance and insurance businesses within our Reinsurance and Lloyd's segments, and Other category. Refer to our "Item 7. Management's Discussion and Analysis of Financial Condition and Results of Operations, Summary of Critical Accounting Estimates, Claims and Claim Expense Reserves" for more information on the risks we insure and reinsure, the reserving techniques, assumptions and processes we follow to estimate our claims and claim expense reserves, and our current estimates versus our initial estimates of our claims reserves, for each of these units.

The following table represents the development of our GAAP balance sheet reserves for December 31, 2002 through December 31, 2012. 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.