The following is a discussion and analysis of our financial condition and results of operations. This should be read in conjunction with our consolidated financial statements included in Item 1 of this report and also our Management's Discussion and Analysis of Financial Condition and Results of Operations contained in our Annual Report on Form 10-K for the year ended December 31, 2011 ("2011 Form 10-K"). In addition, readers should review "Risk Factors" set forth in Item 1A of Part I of our 2011 Form 10-K. Tabular amounts are in U.S. Dollars in thousands, except share amounts, unless otherwise noted.

Arch Capital Group Ltd. ("ACGL" and, together with its subsidiaries, "we" or "us") is a Bermuda public limited liability company with approximately $5.42 billion in capital at June 30, 2012 and, through operations in Bermuda, the United States, Europe and Canada, writes insurance and reinsurance on a worldwide basis. While we are positioned to provide a full range of property and casualty insurance and reinsurance lines, we focus on writing specialty lines of insurance and reinsurance. It is our belief that our underwriting platform, our experienced management team and our strong capital base that is unencumbered by significant pre-2002 risks have enabled us to establish a strong presence in the insurance and reinsurance markets.

Current Outlook

The broad market environment continues to show improvement across the board. From a rate standpoint, almost all lines of business were in positive territory in the 2012 second quarter with rate increases slightly above loss cost trends. In our insurance business, rates were up approximately 4% on a weighted basis. We experienced favorable rate movement on primary lines such as general liability, umbrella liability, auto liability and workers' compensation. Two exceptions to the overall rate trends were in healthcare and surety which experienced moderate rate reductions during the 2012 second quarter. However, even with this improvement in the rate environment, we believe that longer-tail lines still require substantial additional rate improvement to become attractive. In our reinsurance business, rates continued to improve significantly, on a risk adjusted basis, in property and property catastrophe business, with the best increases to date reflected in international, catastrophe exposed businesses. Such improvements were driven, in part, by the impact of the higher level of catastrophic activity in 2010 and 2011. All other lines remained basically unchanged although our reinsurance operations benefited from the underlying rate increases in primary lines noted above. Our underwriting teams continue to execute a disciplined strategy by emphasizing small and medium-sized accounts over large accounts and focusing more on short-tail business.

Our objective is to achieve an average operating return on average equity of 15% or greater over the insurance cycle, which we believe to be an attractive return to our common shareholders given the risks we assume. We continue to look for opportunities to find acceptable books of business to underwrite without sacrificing underwriting discipline and continue to believe that the most attractive area from a pricing point of view remains catastrophe-exposed business. We expect that catastrophe-exposed business will continue to represent a significant proportion of our overall book, which could increase the volatility of our operating results.

The current economic conditions could continue to have a material impact on the frequency and severity of claims and, therefore, could negatively impact our underwriting returns. In addition, volatility in the financial markets could continue to significantly affect our investment returns, reported results and shareholders' equity. We consider the potential impact of economic trends in the estimation process for establishing unpaid losses and loss adjustment expenses and in determining our investment strategies.

In addition, the impact of the continuing weakness of the U.S., European countries and other key economies, projected budget deficits for the U.S., European countries and other governments and the consequences associated with possible additional downgrades of securities of the U.S., European countries and other governments by credit rating agencies is inherently unpredictable and could have a material adverse effect

on financial markets and economic conditions in the U.S. and throughout the world. In turn, this could have a material adverse effect on our business, financial condition and results of operations and, in particular, this could have a material adverse effect on the value of securities in our investment portfolio.

Natural Catastrophe Risk

We monitor our natural catastrophe risk globally for all perils and regions, in each case, where we believe there is significant exposure. Our models employ both proprietary and vendor-based systems and include cross-line correlations for property, marine, offshore energy, aviation, workers compensation and personal accident. Currently, we seek to limit our 1-in-250 year return period net probable maximum pre-tax loss from a severe catastrophic event in any geographic zone to approximately 25% of total shareholders' equity. We reserve the right to change this threshold at any time. Based on in-force exposure estimated as of July 1, 2012, our modeled peak zone catastrophe exposure is a windstorm affecting the Gulf of Mexico, with a net probable maximum pre-tax loss of $878 million, followed by windstorms affecting the Northeastern U.S. and Florida Tri-County with net probable maximum pre-tax losses of $846 million and $645 million, respectively. Based on in-force exposure estimated as of April 1, 2012, our modeled peak zone exposure was a windstorm affecting the Gulf of Mexico, with a net probable maximum pre-tax loss of $860 million, followed by windstorms affecting the Northeastern U.S. and Florida Tri-County with net probable maximum pre-tax losses of $826 million and $608 million, respectively. Our exposures to other perils, such as U.S. earthquake and international events, are less than the exposures arising from U.S. windstorms and hurricanes. As of July 1, 2012, our modeled peak zone earthquake exposure (New Madrid earthquake) represented less than 50% of our peak zone catastrophe exposure, and our modeled peak zone international exposure (Japan earthquake) is substantially less than both our peak zone windstorm and earthquake exposures. Net probable maximum pre-tax loss estimates are net of expected reinsurance recoveries, before income tax and before excess reinsurance reinstatement premiums. Loss estimates are reflective of the zone indicated and not the entire portfolio. Since hurricanes and windstorms can affect more than one zone and make multiple landfalls, our loss estimates include clash estimates from other zones.

The loss estimates shown above do not represent our maximum exposures and it is highly likely that our actual incurred losses would vary materially from the modeled estimates. There can be no assurances that we will not suffer a net loss greater than 25% of our total shareholders' equity from one or more catastrophic events due to several factors, including the inherent uncertainties in estimating the frequency and severity of such events and the margin of error in making such determinations resulting from potential inaccuracies and inadequacies in the data provided by clients and brokers, the modeling techniques and the application of such techniques or as a result of a decision to change the percentage of shareholders' equity exposed to a single catastrophic event. Actual losses may also increase if our reinsurers fail to meet their obligations to us or the reinsurance protections purchased by us are exhausted or are otherwise unavailable. See "Risk Factors-Risk Relating to Our Industry" and "Management's Discussion and Analysis of Financial Condition and Results of Operations-Natural and Man-Made Catastrophic Events" in our 2011 Form 10-K.

Financial Measures

Management uses the following three key financial indicators in evaluating our performance and measuring the overall growth in value generated for ACGL's common shareholders:

Book Value per Common Share

Book value per common share represents total common shareholders' equity divided by the number of common shares outstanding. Management uses growth in book value per common share as a key measure of the value generated for our common shareholders each period and believes that book value per common share is the key driver of ACGL's share price over time. Book value per common share is impacted by, among other factors, our underwriting results, investment returns and share repurchase activity, which has an accretive or dilutive impact on book value per common share depending on the purchase price.

Book value per common share was $34.45 at June 30, 2012, compared to $33.33 at March 31, 2012 and $31.76 at December 31, 2011. The 3.4% change for the 2012 second quarter and 8.5% change for the six months ended June 30, 2012 was generated through operating results and total return on investments. We adopted new accounting guidance effective January 1, 2012 concerning the accounting for costs associated with acquiring or renewing insurance contracts. This guidance was adopted retrospectively and has been applied to all prior period financial information. The adoption of the new accounting guidance reduced the reported book value per common share by $0.27 at December 31, 2011. See Note 3, "Recent Accounting Pronouncements," of the notes accompanying our consolidated financial statements for additional information.

Operating Return on Average Common Equity

Operating return on average common equity ("Operating ROAE") represents after-tax operating income available to common shareholders divided by the average of beginning and ending common shareholders' equity during the period. After-tax operating income available to common shareholders, a "non-GAAP measure" as defined in the SEC rules, represents net income available to common shareholders, excluding net realized gains or losses, net impairment losses recognized in earnings, equity in net income or loss of investment funds accounted for using the equity method and net foreign exchange gains or losses, net of income taxes. Management uses Operating ROAE as a key measure of the return generated to common shareholders and has set an objective to achieve an average Operating ROAE of 15% or greater over the insurance cycle, which it believes to be an attractive return to common shareholders given the risks we assume. See "Comment on Non-GAAP Financial Measures."

Our Operating ROAE was 12.3% for the 2012 second quarter, compared to 5.9% for the 2011 second quarter, and 11.4% for the six months ended June 30, 2012, compared to 3.3% for the 2011 period. The higher Operating ROAE for the 2012 periods primarily resulted from improved underwriting results which reflected a lower level of catastrophic events than in the 2011 periods.

Total Return on Investments

Total return on investments includes net investment income, equity in net income or loss of investment funds accounted for using the equity method, net realized gains and losses and the change in unrealized gains and losses generated by our investment portfolio. Total return is calculated on a pre-tax basis and includes the effect of financial market conditions along with foreign currency fluctuations. Management uses total return on investments as a key measure of the return generated to common shareholders on the capital held in the business, and compares the return generated by our investment portfolio against benchmark returns which we measured our portfolio against during the periods. The benchmark return is a weighted average of the benchmarks assigned to each of our investment managers and vary based on the nature of the portfolios under management.

The benchmark return index is a customized combination of indices intended to approximate a target portfolio by asset mix and average credit quality while also matching the approximate estimated duration and currency mix of our insurance and reinsurance liabilities. Although the estimated duration and average credit quality of this index will move as the duration and rating of its constituent securities change, generally we do not adjust the composition of the benchmark return index. The benchmark return index should not be interpreted as expressing a preference for or aversion to any particular sector or sector weight. The index is intended solely to provide, unlike many master indices that change based on the size of their constituent indices, a relatively stable basket of investable indices.

At June 30, 2012, the benchmark return index had an average credit quality of "Aa1" by Moody's Investors Service ("Moody's"), an estimated duration of 3.18 years and included weightings to the following indices:

                                                                     Weighting
Merrill Lynch Unsubordinated U.S. Treasuries/Agencies, 1-10
Years Index                                                              30.875 %
Merrill Lynch U.S. Corporates and All Yankees, 1-10 Years Index          20.875 %
Merrill Lynch Mortgage Master Index                                      11.875 %
Barclays Capital CMBS, AAA Index                                         10.000 %
Merrill Lynch Municipals, 1-10 Years Index                                7.125 %
MSCI World Free Index                                                     5.000 %
Merrill Lynch U.S. Treasury Bills, 0-3 Months Index                       4.750 %
Merrill Lynch U.S. High Yield Master II Constrained Index                 2.375 %
Barclays Capital U.S. High-Yield Corporate Loan Index                     2.375 %
Merrill Lynch U.K. Gilts, 1-10 Years Index                                2.375 %
Merrill Lynch EMU Direct Government 1-10 Years Index                      2.375 %
Total                                                                   100.000 %

The following table summarizes the pre-tax total return (before investment expenses) of our investment portfolio compared to the benchmark return against which we measured our portfolio during the periods:

                                                         Arch        Benchmark
                                                     Portfolio (1)    Return

Pre-tax total return (before investment expenses):
2012 second quarter                                           0.63 %      0.86 %
2011 second quarter                                           1.65 %      1.93 %

Six months ended June 30, 2012                                2.53 %      2.43 %
Six months ended June 30, 2011                                3.17 %      2.87 %

For the 2012 second quarter, total return on our portfolio reflected unfavorable returns on equities, reflecting the decline in the S&P 500 index during the period along with underperformance of commodity-related securities. Our portfolio underperformed the benchmark return by 23 basis points for the 2012 second quarter, due in part to an overweighting in certain sector allocations to the benchmark return. Excluding foreign exchange, total return was 1.04% for the 2012 second quarter, compared to 1.54% for the 2011 second quarter, and 2.66% for the six months ended June 30, 2012, compared to 2.69% for the 2011 period.

Comment on Non-GAAP Financial Measures

Throughout this filing, we present our operations in the way we believe will be the most meaningful and useful to investors, analysts, rating agencies and others who use our financial information in evaluating the performance of our company. This presentation includes the use of after-tax operating income available to common shareholders, which is defined as net income available to common shareholders, excluding net realized gains or losses, net impairment losses recognized in earnings, equity in net income or loss of investment funds accounted for using the equity method and net foreign exchange gains or losses, net of income taxes. The presentation of after-tax operating income available to common shareholders is a "non-GAAP financial measure" as defined in Regulation G. The reconciliation of such measure to net income available to common shareholders (the most directly comparable GAAP financial measure) in accordance with Regulation G is included under "Results of Operations" below.

We believe that net realized gains or losses, net impairment losses recognized in earnings, equity in net income or loss of investment funds accounted for using the equity method and net foreign exchange gains or losses in any particular period are not indicative of the performance of, or trends in, our business. Although net realized gains or losses, net impairment losses recognized in earnings, equity in net income or loss of investment

funds accounted for using the equity method and net foreign exchange gains or losses are an integral part of our operations, the decision to realize investment gains or losses, the recognition of net impairment losses, the recognition of equity in net income or loss of investment funds accounted for using the equity method and the recognition of foreign exchange gains or losses are independent of the insurance underwriting process and result, in large part, from general economic and financial market conditions. Furthermore, certain users of our financial information believe that, for many companies, the timing of the realization of investment gains or losses is largely opportunistic. In addition, net impairment losses recognized in earnings on our investments represent other-than-temporary declines in expected recovery values on securities without actual realization. The use of the equity method on certain of our investments in certain funds that invest in fixed maturity securities is driven by the ownership structure of such funds (either limited partnerships or limited liability companies). In applying the equity method, these investments are initially recorded at cost and are subsequently adjusted based on our proportionate share of the net income or loss of the funds (which include changes in the market value of the underlying securities in the funds). This method of accounting is different from the way we account for our other fixed maturity securities and the timing of the recognition of equity in net income or loss of investment funds accounted for using the equity method may differ from gains or losses in the future upon sale or maturity of such investments. Due to these reasons, we exclude net realized gains or losses, net impairment losses recognized in earnings, equity in net income or loss of investment funds accounted for using the equity method and net foreign exchange gains or losses from the calculation of after-tax operating income available to common shareholders.

We believe that showing net income available to common shareholders exclusive of the items referred to above reflects the underlying fundamentals of our business since we evaluate the performance of and manage our business to produce an underwriting profit. In addition to presenting net income available to common shareholders, we believe that this presentation enables investors and other users of our financial information to analyze our performance in a manner similar to how management analyzes performance. We also believe that this measure follows industry practice and, therefore, allows the users of financial information to compare our performance with our industry peer group. We believe that the equity analysts and certain rating agencies which follow us and the insurance industry as a whole generally exclude these items from their analyses for the same reasons.

RESULTS OF OPERATIONS



The following table summarizes, on an after-tax basis, our consolidated
financial data, including a reconciliation of after-tax operating income
available to common shareholders to net income available to common shareholders:



                                       Three Months Ended            Six Months Ended
                                            June 30,                     June 30,
                                       2012           2011          2012          2011

After-tax operating income
available to common shareholders    $   141,400    $   59,739    $  255,060    $   67,315
Net realized gains, net of tax           33,275        44,799        74,148        66,384
Net impairment losses recognized
in earnings, net of tax                  (1,951 )      (1,684 )      (2,974 )      (4,364 )
Equity in net income of
investment funds accounted for
using the equity method, net of
tax                                       7,787         5,973        32,613        35,646
Net foreign exchange gains
(losses), net of tax                     32,108       (18,685 )      11,567       (55,827 )
Net income available to common
shareholders                        $   212,619    $   90,142    $  370,414    $  109,154

The increase in after-tax operating income in the 2012 periods compared to the 2011 periods primarily resulted from improved underwriting results which reflected a lower level of catastrophic loss activity. Our results included losses for current year catastrophic events of $7.2 million, net of reinsurance and reinstatement premiums, in the 2012 second quarter, compared to $95.0 million in the 2011 second quarter, and $30.2 million for the six months ended June 30, 2012, compared to $273.7 million for the 2011 period.

Segment Information

We classify our businesses into two underwriting segments - insurance and reinsurance - and corporate and other (non-underwriting). Management measures segment performance based on underwriting income or loss. We do not manage our assets by segment and, accordingly, investment income is not allocated to each underwriting segment. In addition, other revenue and expense items are not evaluated by segment.

Insurance Segment



The following table sets forth our insurance segment's underwriting results:



                           Three Months Ended June 30,           Six Months Ended June 30,
                           2012        2011      % Change      2012          2011       % Change

Gross premiums
written                 $  676,090   $ 635,005        6.5   $ 1,364,203   $ 1,269,588        7.5
Net premiums written       464,584     438,263        6.0       955,264       887,554        7.6

Net premiums earned     $  446,594   $ 410,819        8.7   $   888,334   $   818,410        8.5
Fee income                     628         702                    1,158         1,480
Losses and loss
adjustment expenses       (290,416 )  (301,642 )               (593,580 )    (599,365 )
Acquisition expenses,
net                        (76,058 )   (66,543 )               (149,928 )    (127,958 )
Other operating
expenses                   (76,617 )   (77,774 )               (149,987 )    (152,403 )
Underwriting income
(loss)                  $    4,131   $ (34,438 )      n/m   $    (4,003 ) $   (59,836 )      n/m




                                               % Point                   % Point
Underwriting Ratios                            Change                    Change
Loss ratio                      65.0 %  73.4 %    (8.4 )  66.8 %  73.2 %    (6.4 )
Acquisition expense ratio (1)   16.9 %  16.0 %     0.9    16.7 %  15.5 %     1.2
Other operating expense ratio   17.2 %  18.9 %    (1.7 )  16.9 %  18.6 %    (1.7 )
Combined ratio                  99.1 % 108.3 %    (9.2 ) 100.4 % 107.3 %    (6.9 )

The components of the insurance segment's underwriting results are discussed below.

Premiums Written.



The following table sets forth our insurance segment's net premiums written by
major line of business:



                          Three Months Ended June 30,                Six Months Ended June 30,
                            2012                 2011                2012                2011
                      Amount        %       Amount       %      Amount       %      Amount       %

Programs            $    92,998       20   $  81,629      19   $ 174,614      18   $ 156,025      18
Property, energy,
marine and
aviation                 86,390       19     103,296      24     166,209      17     179,714      20
Professional
liability                65,198       14      57,906      13     135,759      14     117,291      13
Executive
assurance                60,205       13      53,974      12     128,583      13     110,042      12
Construction             49,784       11      42,408      10      83,437       9      73,917       8
Casualty                 30,638        7      24,939       6      57,611       6      55,073       6
Travel and
accident                 20,294        4      19,284       4      43,130       5      40,785       5
Lenders products         20,477        4      21,526       5      42,892       4      42,600       5
National accounts         4,961        1       4,397       1      40,399       4      44,588       5
Surety                   12,723        3       9,618       2      24,857       3      19,352       2
Healthcare                7,959        2       8,422       2      18,594       2      17,539       2
Other (1)                12,957        2      10,864       2      39,179       5      30,628       4

2012 second quarter versus 2011. Increases in programs, professional liability and construction business were partially offset by a lower level of onshore energy business (included in the 'property, energy, marine and aviation' line). The higher level of program business was primarily due to growth in exposures on existing accounts and rate improvements while the higher level of professional liability business primarily resulted from an increase in international small and medium sized accounts. The increase in construction business was primarily due to activity on an existing account which is not expected to recur, while the reduction in onshore energy premiums reflected lower renewals in reaction to . . .