Exhibit 99.1

ALLEGHANY ANNOUNCES CLOSING OF INITIAL PUBLIC OFFERING OF COMMON STOCK OF DARWIN
PROFESSIONAL UNDERWRITERS, INC. AND EXERCISE OF OVER-ALLOTMENT OPTION

     May 24, 2006 (New York, NY) -- Alleghany Corporation (NYSE-Y) ("Alleghany")
announced today the closing of the previously announced initial public offering
(the "IPO") of the common stock of its subsidiary Darwin Professional
Underwriters, Inc. (NYSE Arca: DR) ("Darwin"). The sale in the IPO of 6,000,000
shares of common stock at $16.00 per share yielded gross proceeds of $96 million
and net proceeds of approximately $86.3 million. These amounts reflect the
exercise by the underwriters of their over-allotment option to purchase an
additional 782,609 shares of Darwin's common stock. All of the proceeds of the
IPO, after deduction of underwriting discounts and commissions and payment of
offering expenses, were used to reduce Alleghany's equity interest in Darwin.
After the IPO, Alleghany continues to own approximately 55.0% of the issued and
outstanding shares of common stock of Darwin.

     Merrill Lynch & Co. and Credit Suisse Securities (USA) LLC acted as joint
book-running managers for the offering. Details of the IPO, including a detailed
description of Darwin's common stock and certain risk factors involved in
investing in Darwin's common stock, are contained in a prospectus. Copies of the
prospectus may be obtained from Merrill Lynch, Pierce, Fenner & Smith
Incorporated, 4 World Financial Center, FL 05, New York, NY 10080, or Credit
Suisse Securities (USA) LLC, Prospectus Department, One Madison Avenue, New
York, NY 10010.

     This press release shall not constitute an offer to sell or the
solicitation of an offer to buy, nor shall there be any sale of these securities
in any state or jurisdiction in which the offer, solicitation or sale would be
unlawful prior to registration or qualification under the securities laws of any
such state or jurisdiction.

     This press release contains forward looking statements with respect to the
anticipated effects of the transaction. Actual results of the transaction could
be significantly different. Factors that could affect results include those set
forth in filings made by Alleghany and by Darwin with the SEC. Although
forward-looking statements help provide complete information about future
prospects, readers should keep in mind that forward-looking statements are much
less reliable than historical information.

     Alleghany is engaged through its subsidiary Alleghany Insurance Holdings
LLC (consisting of RSUI Group, Inc., Capitol Transamerica Corporation and
Darwin) in the property and casualty insurance business. Darwin is a specialty
insurance company focused on the professional liability insurance market and in
particular on the directors and officers ("D&O"), errors and omissions ("E&O")
and medical malpractice liability lines.



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