Alterra Capital Holdings Limited (“Alterra”) (NASDAQ: ALTE; BSX: ALTE.BH) today announced that its initial estimate for losses from third quarter 2012 catastrophe events, predominantly from Hurricane Isaac, is in the range of $10 million to $15 million, pretax and net of reinsurance and reinstatement premiums. Losses are expected to relate principally to Alterra’s US insurance segment. In addition, Alterra believes that its net underwriting loss from the US crop events that occurred in the summer of 2012 will be approximately $22.5 million, pretax and net of reinsurance and reinstatement premiums, within the previously announced range. Alterra’s loss estimates are based on proprietary modeling analyses, industry assessments of exposure, claims information obtained from Alterra's clients and brokers to date, and a review of in-force contracts. Alterra's actual losses from these events may vary materially from the estimates due to the inherent uncertainties in making such determinations resulting from several factors, including the preliminary nature of available information, the potential inaccuracies and inadequacies in the data provided by clients and brokers, the modeling techniques employed 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 Alterra's reinsurers fail to meet their obligations to Alterra or the reinsurance protections purchased by Alterra are exhausted or are otherwise unavailable. About Alterra Capital Holdings Limited Alterra Capital Holdings Limited is a global enterprise dedicated to providing diversified specialty insurance and reinsurance products to corporations, public entities, and property and casualty insurers. Cautionary Note Regarding Forward-Looking Statements This release includes forward-looking statements that reflect Alterra’s current views with respect to future events and financial performance. In particular, statements regarding future rate movements are forward looking statements. These forward-looking statements are subject to certain risks and uncertainties that could cause actual results to differ materially from those suggested by such statements. For further information regarding cautionary statements and factors affecting Alterra’s future results, please refer to the most recent reports on Form 10-K and Form 10-Q and other documents filed by Alterra with the SEC. Alterra undertakes no obligation to update or revise publicly any forward-looking statement whether as a result of new information, future developments or otherwise.