8-K

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

September 29, 2008

Date of Report (Date of earliest event reported)

Arch Capital Group Ltd.

(Exact name of registrant as specified in its charter)

Bermuda	0-26456	N/A
(State or other jurisdiction of incorporation or organization)	(Commission File Number)	(I.R.S. Employer Identification No.)

Wessex House, 45 Reid Street, Hamilton HM 12, Bermuda

(Address of principal executive offices) (Zip Code)

Registrant’s telephone number, including area code:
(441) 278-9250

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):

[     ]	Written communications pursuant to Rule 425 under the Securities Act (17 CFR 230.425)
[     ]	Soliciting material pursuant to Rule 14a-12 under the Exchange Act (17 CFR 240.14a-12)
[     ]	Pre-commencement communications pursuant to Rule 14d-2(b) under the Exchange Act (17 CFR 240.14d-2(b))
[     ]	Pre-commencement communications pursuant to Rule 13e-4(c) under the Exchange Act (17 CFR 240.13e-4(c))

ITEM 7.01 Regulation FD Disclosure.

On September 29, 2008, Arch Capital Group Ltd. issued a press release providing information on recent catastrophic activity and other market events.  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 9.01 Financial Statements and Exhibits.

EXHIBIT NO.	DESCRIPTION
99.1	Press Release dated September 29, 2008 providing information on recent catastrophic activity and other market events.

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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.

	ARCH CAPITAL GROUP LTD.
Date: September 29, 2008	By:	/s/ Marc Grandisson
		Name: Marc Grandisson
		Title:	Chairman & Chief Executive Officer of Arch Worldwide Reinsurance Group

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EXHIBIT INDEX

EXHIBIT NO.	DESCRIPTION
99.1	Press Release dated September 29, 2008 providing information on recent catastrophic activity and other market events.

EX-99.1

Exhibit 99.1

ARCH CAPITAL GROUP LTD. PROVIDES INFORMATION ON

RECENT CATASTROPHIC ACTIVITY AND OTHER MARKET  EVENTS

HAMILTON, BERMUDA, SEPTEMBER 29, 2008 –  Arch Capital Group Ltd. [Nasdaq: ACGL] today announced that it expects pre-tax earnings for the 2008 third quarter to be negatively impacted by the effects of Hurricanes Gustav and Ike in the range of $105 million to $180 million, net of reinsurance and reinstatement premiums.  The Company’s preliminary net loss estimate for Hurricane Gustav is in the range of $15 million to $30 million based on industry insured losses of $2.5 billion to $4.5 billion.  The preliminary net loss estimate for Hurricane Ike is in the range of $90 million to $150 million based on industry insured losses of $8 billion to $12 billion.

The losses from the storms are currently estimated to arise 30% in our insurance operations and 70% in our reinsurance operations.  As previously reported, a significant portion of the Company’s catastrophe-exposed business is written by a Bermuda-based subsidiary.  As a result, generally, the Company’s effective tax rate is likely to be adversely impacted in periods with significant catastrophic claims activity.

The above hurricane loss estimates are based on currently available information derived from modeling techniques, industry assessments of exposure, preliminary claims information obtained from the Company’s clients and brokers to date and a review of the Company’s in-force contracts.  The Company’s actual losses from this event may vary materially from the estimates due to the inherent uncertainties in making such determinations resulting from several factors, including the preliminary nature of the available information, the potential inaccuracies and inadequacies in the data provided by clients and brokers, the modeling techniques and the application of such techniques, the contingent nature of business interruption exposures, the effects of any resultant demand surge on claims activity and attendant coverage issues.  In addition, actual losses may increase if the Company’s reinsurers fail to meet their obligations to the Company or the reinsurance protections purchased by the Company are exhausted or are otherwise unavailable.

In addition, the Company also announced that its investment portfolio does not include direct ownership of common stock or preferred stock of any publicly-traded issuers.  The portfolio’s exposures to publicly-traded equity securities include investments in equity index funds, which had an aggregate fair market value of $106.2 million at June 30, 2008.  With respect to its fixed income portfolio, the Company has no exposure to fixed income securities issued directly by American International Group, Inc. (AIG) and held fixed income securities of subsidiaries of AIG in the amount of $16.9 million at June 30, 2008 fair market values.  The Company held fixed income securities issued by Lehman Brothers Holdings Inc. in the amount of $26.3 million at June 30, 2008 fair market values.

Arch Capital Group Ltd., a Bermuda-based company with approximately $4.3 billion in capital at June 30, 2008, provides insurance and reinsurance on a worldwide basis through its wholly owned subsidiaries.

Cautionary Note Regarding Forward-Looking Statements

The Private Securities Litigation Reform Act of 1995 provides a “safe harbor” for forward-looking statements. This release or any other written or oral statements made by or on behalf of Arch Capital Group Ltd. and its subsidiaries may include forward-looking statements, which reflect our current views with respect to future events and financial performance. All statements other than statements of historical fact included in or incorporated by reference in this release are forward-looking statements.

Forward-looking statements can generally be identified by the use of forward-looking terminology such as “may,” “will,” “expect,” “intend,” “estimate,” “anticipate,” “believe” or “continue” or their negative or variations or similar terminology. Forward-looking statements involve our current assessment of risks and uncertainties. Actual events and results may differ materially from those expressed or implied in these statements. A non-exclusive list of the important factors that could cause actual results to differ materially from those in such forward-looking statements includes the following: adverse general economic and market conditions; increased competition; pricing and policy term trends; fluctuations in the actions of rating agencies and our ability to

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maintain and improve our ratings; investment performance; the loss of key personnel; the adequacy of our loss reserves, severity and/or frequency of losses, greater than expected loss ratios and adverse development on claim and/or claim expense liabilities; greater frequency or severity of unpredictable natural and man-made catastrophic events; the impact of acts of terrorism and acts of war; changes in regulations and/or tax laws in the United States or elsewhere; our ability to successfully integrate, establish and maintain operating procedures as well as integrate the businesses we have acquired or may acquire into the existing operations; changes in accounting principles or policies; material differences between actual and expected assessments for guaranty funds and mandatory pooling arrangements; availability and cost to us of reinsurance to manage our gross and net exposures; the failure of others to meet their obligations to us; and other factors identified in our filings with the U.S. Securities and Exchange Commission.

The foregoing review of important factors should not be construed as exhaustive and should be read in conjunction with other cautionary statements that are included herein or elsewhere. All subsequent written and oral forward-looking statements attributable to us or persons acting on our behalf are expressly qualified in their entirety by these cautionary statements. We undertake no obligation to publicly update or revise any forward-looking statement, whether as a result of new information, future events or otherwise.

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Contact:	Arch Capital Group Ltd.
	John D. Vollaro
	(441) 278-9250

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