Exhibit 99.1

ALLEGHANY CORPORATION

7 Times Square Tower, 17^th Floor

New York, NY 10036

ALLEGHANY CORPORATION REPORTS 2013 SECOND QUARTER RESULTS

NEW YORK, NY, August 5, 2013 – Alleghany Corporation (NYSE-Y) today announced its financial results for the three and six months ended June 30, 2013. Stockholders’ equity per common share grew to $387.59 as of June 30, 2013, an increase of 2.2% from stockholders’ equity per common share of $379.13 at 2012 year-end. Alleghany reported net earnings of $113.7 million, or $6.78 per diluted share for the 2013 second quarter, compared with $109.3 million, or $6.45 per diluted share for the 2012 second quarter. For the first six months of 2013, Alleghany reported net earnings of $310.0 million, or $18.45 per diluted share, compared with $669.4 million, or $47.96 per diluted share for the first six months of 2012. Net earnings for the first six months of 2012 include 116 days of results of TransRe as well as merger-related items associated with the purchase of TransRe, including a gain of $494.9 million resulting from the application of purchase accounting treatment, amortization of intangible assets of $140.0 million and transaction costs of $33.8 million.

Highlights for the second quarter and first six months include:

A summary of Alleghany’s pre-tax results for the three and six months ended June 30, 2013 and 2012 follows:

Weston M. Hicks, President and chief executive officer, commented, “Our insurance and reinsurance businesses performed well in the second quarter. TransRe had strong results, generating an underwriting profit of $60.5 million and a combined ratio of 92.8%, despite $45.1 million of catastrophe losses from European and Canadian floods, compared with an adjusted 92% combined ratio estimate (adjusted to exclude the impact of the application of the acquisition method of accounting) in the catastrophe-free second quarter of last year. TransRe’s gross premiums written decreased by 7.1% in the second quarter, as the company continues to exercise discipline in allocating capital to the most profitable opportunities in a reinsurance environment characterized by competitive pricing in many lines and a decreasing amount of risk premium being ceded by insurers. TransRe has a strong franchise and an efficient cost structure that affords it the ability to avoid chasing top line growth simply to cover overhead costs.”

“Our insurance businesses also performed well, posting a 92.1% combined ratio in the quarter compared with 94.9% in the second quarter of last year. The results were led by RSUI which grew gross premiums written by 8.3% in the second quarter and continued its track record of strong underwriting performance, producing an underwriting profit of $26.0 million and an 86.2% combined ratio. RSUI’s premium growth was due to stable renewal retention rates, strong new business submissions and modest price increases for casualty business.”

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“We grew our book value per share by 2.2% in the first six months of 2013, but book value was down 1.8% in the second quarter due to the impact of rising interest rates. The total return on our investment portfolio for the quarter was (1.2%), and 0.2% for the first six months of the year, with strong equity returns mitigating fixed income losses. Our investment strategy remains focused on balancing interest rate risk by combining an intermediate duration fixed income portfolio with exposure to equity securities that have performed well in rising interest rate environments. We believe that our recently-announced strategic relationship with Ares Management will provide an additional interest-rate hedge through an allocation to credit strategies with floating interest rates.”

In the first six months of 2013, Alleghany repurchased an aggregate of 113,160 shares of its common stock in the open market for $40.4 million at an average price per share of $356.92, of which 23,409 shares were repurchased in the second quarter of 2013 for $8.8 million at an average price per share of $376.49. Following this activity, Alleghany had $241.9 million remaining on its currently effective $300 million share repurchase authorization.

2013 Second Quarter Underwriting Results

Alleghany’s underwriting profit for the second quarter of 2013 was $78.8 million, compared with a $175.9 million underwriting profit for the second quarter of 2012. The underwriting results for the 2013 second quarter reflect a $60.5 million underwriting profit for the reinsurance segment (TransRe), compared with a $165.5 million underwriting profit for the 2012 second quarter, and an underwriting profit of $18.3 million for the insurance segment, compared with a $10.4 million underwriting profit for the 2012 second quarter.

The decrease in reinsurance segment underwriting profit in the second quarter of 2013 from the second quarter of 2012 primarily reflects the absence of merger-related accounting items in the 2013 second quarter, which were significant in the 2012 second quarter. In particular, the significant increase in commissions, brokerage and other underwriting expenses reflects the absence of the beneficial impact of the acquisition method of accounting on such expenses in the 2012 second quarter. The increase in insurance segment underwriting profit in the second quarter of 2013 from the second quarter of 2012 primarily reflects lack of net adverse prior year reserve development at CATA, which was significant in the second quarter of 2012.

Total net premiums written for the 2013 second quarter were $1,158.5 million, compared with $1,223.7 million for the 2012 second quarter. TransRe’s net premiums written for the 2013 second quarter decreased by 10.6% to $843.3 million from the 2012 second quarter, primarily reflecting an increasingly competitive reinsurance market and a decreasing amount of risk premium being ceded by insurers. The insurance segment’s net premiums written for the quarter increased by 12.3% to $315.2 million from the 2012 second quarter, primarily due to new business written and modest casualty price increases.

Alleghany’s combined ratio for the 2013 second quarter was 92.6%, compared with 83.9% in the 2012 second quarter. The reinsurance segment’s combined ratio for the 2013 second quarter was 92.8%, compared with 81.5% for the 2012 second quarter, and the insurance segment’s combined ratio for the quarter was 92.1%, compared with 94.9% for the 2012 second quarter. As explained above, the reinsurance segment’s combined ratio in the second quarter of 2012 was favorably impacted as a result of applying the acquisition method of accounting for the merger. Excluding the impact of the application of the acquisition method of accounting, TransRe’s estimated combined ratio was approximately 92% for the second quarter of 2012.

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First Six Months of 2013 Underwriting Results

Alleghany’s underwriting profit for the first six months of 2013 was $260.2 million, compared with a $276.2 million profit for the first six months of 2012. The underwriting results reflect a $191.9 million underwriting profit for the reinsurance segment (TransRe), compared with a $231.7 million underwriting profit for first six months of 2012 in the 116-day period of Alleghany’s ownership of TransRe, and a $68.3 million underwriting profit for the insurance segment, compared with a $44.5 million underwriting profit for the first six months of 2012.

The decrease in reinsurance segment underwriting profit in the first six months of 2013 from the first six months of 2012 primarily reflects an increase in commissions, brokerage and other underwriting expenses relative to net premiums earned. As explained above, the first six months of 2013 reflected the absence of favorable impact arising from the acquisition method of accounting, which was significant in the first six months of 2012.

The increase in insurance segment underwriting profit in the first six months of 2013 from the first six months of 2012 primarily reflects the absence of net adverse prior year reserve development at CATA, which was significant in the second quarter of 2012, and the positive impact of growing premiums at RSUI.

Total net premiums written for the first six months of 2013 were $2,252.5 million, compared with $1,657.9 million for the first six months of 2012. The reinsurance segment’s net premiums written for the first six months of 2013 increased by 45.0% to $1,709.3 million from the first six months of 2012, primarily reflecting the fact that the first six months of 2012 did not include net premiums written by TransRe prior to the March 6, 2012 merger date. The insurance segment’s net premiums written for the first six months of 2013 increased by 13.5% to $543.2 million from the first six months of 2012, primarily due to new business written and modest casualty price increases.

Alleghany’s combined ratio for the first six months of 2013 was 87.8%, compared with 82.0% in the first six months of 2012. TransRe’s combined ratio for the first six months of 2013 was 88.6%, compared with 79.6% for the first six months of 2012, and the insurance segment’s combined ratio was 85.0%, compared with 88.7% for the first six months of 2012. As noted above, TransRe’s combined ratio was favorably impacted as a result of applying the acquisition method of accounting for the merger because deferred acquisition costs were written off at the March 6, 2012 merger date. As of March 6, 2013, the application of the acquisition method of accounting no longer has a significant impact on TransRe’s combined ratio. Excluding the impact of the application of the acquisition method of accounting, TransRe’s estimated combined ratio was approximately 89% and 91% for the first six months of 2013 and 2012, respectively.

Investment Performance

Alleghany’s net investment income for the three and six months ended June 30, 2013 was $100.4 million and $219.2 million, respectively, an increase of 10.5% and 52.1% over the corresponding 2012 periods. The 52.1% increase in the first six months of 2013 primarily reflects the fact that the first six months of 2012 did not include net investment income of TransRe prior to the March 6, 2012 merger date. The interest income earned on TransRe’s fixed income portfolio is net of a significant increase to amortization expense resulting from the write-up of the portfolio’s amortized cost basis to its fair value as of the date of the merger. This increased amortization expense reduced TransRe’s reported net investment income, compared with TransRe’s net investment income prior to the merger.

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Additional Information

Additional information regarding Alleghany’s 2013 second quarter and year-to-date financial results, including management’s discussion and analysis of Alleghany’s financial condition and results of operations, is contained in Alleghany’s Quarterly Report on Form 10-Q for the period ended June 30, 2013, to be filed with the U.S. Securities and Exchange Commission (the “SEC”) on or about the date hereof. The Form 10-Q will be available on Alleghany’s website at www.alleghany.com and on the SEC’s website at www.sec.gov. Readers are urged to review the Form 10-Q for a more complete discussion of Alleghany’s financial performance.

About Alleghany Corporation

Alleghany Corporation (NYSE-Y) creates value through owning and managing operating subsidiaries and investments, anchored by a core position in property and casualty reinsurance and insurance. Alleghany’s property and casualty subsidiaries include: Transatlantic Holdings, Inc., a leading global reinsurer; RSUI Group, Inc., a national underwriter of property and liability specialty insurance coverages; Capitol Transamerica Corporation, an underwriter of small commercial property, casualty and surety insurance coverages; and Pacific Compensation Corporation, an underwriter of workers’ compensation insurance primarily in California.

Non-GAAP Financial Measures

Throughout this press release, Alleghany’s results of operations have been presented in the way that Alleghany believes will be the most meaningful and useful to investors, analysts, rating agencies and others who use financial information in evaluating the performance of Alleghany. This presentation includes the use of underwriting profit and net earnings before merger-related items and income taxes, which are “non-GAAP financial measures,” as such term is defined in Regulation G promulgated by the SEC.

Underwriting profit represents net premiums earned less net loss and loss adjustment expense and commissions, brokerage and other underwriting expenses, all as determined in accordance with U.S. GAAP, and does not include net investment income, net realized capital gains, other than temporary impairment losses, other income, other operating expenses, amortization of intangible assets or interest expense. Alleghany consistently uses underwriting profit as a supplement to earnings before income taxes, the most comparable U.S. GAAP financial measure, to evaluate the performance of its segments and believes that underwriting profit provides useful additional information to investors because it highlights net earnings attributable to a segment’s underwriting performance. Earnings before income taxes may show a profit despite an underlying underwriting loss, and when underwriting losses persist over extended periods, a reinsurance or an insurance company’s ability to continue as an ongoing concern may be at risk.

Net earnings before merger-related items and income taxes represents earnings before income taxes, excluding gain on bargain purchase, amortization of intangible assets and merger-related transaction costs, all as determined in accordance with U.S. GAAP. Alleghany uses net earnings before merger-related items and income taxes as a supplement to earnings before income taxes, the most comparable U.S. GAAP financial measure, to provide useful additional information to investors by highlighting earnings before income taxes attributable to its performance exclusive of non-recurring merger-related impacts.

These non-GAAP financial measures are not meant to be considered in isolation or as a substitute for measures of operating performance prepared in accordance with U.S. GAAP. Reconciliation of underwriting profit to earnings before income taxes and net earnings before merger-related items and income taxes to earnings before income taxes is presented in the schedules included herein.

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Forward-looking Statements

This release contains disclosures which are forward-looking statements as defined in the Private Securities Litigation Reform Act of 1995. Forward-looking statements include all statements that do not relate solely to historical or current facts, and can be identified by the use of words such as “may,” “will,” “expect,” “project,” “estimate,” “anticipate,” “plan,” “believe,” “potential,” “should,” “continue” or the negative versions of those words or other comparable words. These forward-looking statements are based upon Alleghany’s current plans or expectations and are subject to a number of uncertainties and risks that could significantly affect current plans, anticipated actions and Alleghany’s future financial condition and results. These statements are not guarantees of future performance, and Alleghany has no specific intention to update these statements. The uncertainties and risks include, but are not limited to,

Additional risks and uncertainties include general economic and political conditions, including the effects of a prolonged U.S. or global economic downturn or recession; changes in costs; variations in political, economic or other factors; risks relating to conducting operations in a competitive environment; effects of acquisition and disposition activities, inflation rates, or recessionary or expansive trends; changes in interest rates; extended labor disruptions, civil unrest, or other external factors over which Alleghany has no control; and changes in Alleghany’s plans, strategies, objectives, expectations, or intentions, which may happen at any time at its discretion. As a consequence, current plans, anticipated actions, and future financial condition and results may differ from those expressed in any forward-looking statements made by Alleghany or on its behalf.

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For more information, please contact:

Jeff Majtyka/Mike Smargiassi

Brainerd Communicators, Inc.

212-986-6667

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ALLEGHANY CORPORATION AND SUBSIDIARIES

Consolidated Balance Sheets

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ALLEGHANY CORPORATION AND SUBSIDIARIES

Consolidated Statements of Earnings and Comprehensive Income

(unaudited)

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ALLEGHANY CORPORATION AND SUBSIDIARIES

Consolidated Statements of Earnings and Comprehensive Income

(unaudited)

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ALLEGHANY CORPORATION AND SUBSIDIARIES

Cash and Investments

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ALLEGHANY CORPORATION AND SUBSIDIARIES

Net Investment Income

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ALLEGHANY CORPORATION AND SUBSIDIARIES

Financial Statement Portfolio Return

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ALLEGHANY CORPORATION AND SUBSIDIARIES

Premiums Written