UNITED STATES

SECURITIES AND EXCHANGE COMMISSION
Washington, D.C.  20549

FORM 8-K

Current Report Pursuant to Section 13 or 15(d)
of the Securities Exchange Act of 1934

May 9, 2008

Date of Report (Date of earliest event reported)

Arch Capital Group Ltd.

(Exact name of registrant as specified in its charter)

N/A

(Former name or former address, if changed since last report)

Check the appropriate box below if the Form 8-K filing is intended to simultaneously satisfy the filing obligation of the registrant under any of the following provisions (see General Instruction A.2. below):

ITEM 7.01             Regulation FD Disclosure.

On May 12, 2008, Arch Capital Group Ltd. (“ACGL”) issued a press release announcing that its Board of Directors (the “Board”) approved an additional share repurchase authorization (the “Additional Repurchase Authorization”).  A copy of this press release is attached to this Current Report on Form 8-K as Exhibit 99.1 and is incorporated herein by reference.

The information in this Current Report on Form 8-K, including the information set forth in Exhibit 99.1, shall not be deemed “filed” for purposes of Section 18 of the Securities Exchange Act of 1934, as amended (the “Exchange Act”), or incorporated by reference in any filing under the Securities Act of 1933, as amended, or the Exchange Act, except as shall be expressly set forth by specific reference in such a filing.

ITEM 8.01             Other Events.

Waiver Under Shareholders Agreement.  As previously disclosed, ACGL has agreed (until 2011) not to declare any dividend or make any other distribution on its common shares, and not to repurchase any common shares, until ACGL has repurchased from the Warburg Pincus funds common shares having an aggregate value of $250 million, at a per share price acceptable to these funds.  In connection with the Additional Repurchase Authorization (defined above), the Warburg Pincus funds waived these rights under the shareholders agreement for all repurchases of common shares by ACGL under the Additional Repurchase Authorization in open market transactions and certain privately negotiated transactions.  The shareholders agreement is included as Exhibit 4.3 to ACGL’s Form 10-K for the year ended December 31, 2005.

Preferred Share Dividends.  On May 9, 2008, the Board declared dividends with respect to the outstanding (1) 8,000,000 shares of its 8.00% Non-Cumulative Preferred Shares, Series A, $0.01 per share (the “Series A Shares”), with a liquidation preference of $25.00 per share, and (2) 5,000,000 shares of its 7.875% Non-Cumulative Preferred Shares, Series B, $0.01 per share (the “Series B Shares”), with a liquidation preference of $25.00 per share, as outlined below.  All such dividends will be payable out of lawfully available funds for the payment of dividends under Bermuda law on August 15, 2008 to holders of record of the Series A Shares and the Series B Shares, as applicable, as of August 1, 2008, unless determined otherwise by the Board or the Executive Committee of the Board on or prior to the applicable effective date.

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ITEM 9.01             Financial Statements and Exhibits.

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SIGNATURES

Pursuant to the requirements of the Securities Exchange Act of 1934, as amended, the registrant has duly caused this report to be signed on its behalf by the undersigned.

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EXHIBIT INDEX