Mitsui Sumitomo to Acquire W. R. Berkley's Reinsurance Arm for $1.5 Billion in Overseas Push

Japan's announced Tuesday it's acquiring 's reinsurance unit, Berkley Re, for approximately . The all-cash deal marks a significant strategic move by the Japanese insurer to diversify its portfolio away from its home market, which is highly exposed to natural catastrophes.

Deal at a Glance

The acquisition will see , a core unit of , take full ownership of Berkley Re. According to a joint statement, the transaction is expected to close in the second quarter of , pending regulatory approvals. The acquired entity will be rebranded as Mitsui Sumitomo Reinsurance and will continue to be led by its current CEO, .

Berkley Re wrote in net premiums in and held net assets of as of September 30, 2025.

Strategic Rationale: A Hedge Against Climate Risk

For , the acquisition is a direct play to expand its international reinsurance business and reduce its concentration risk in Japan. The country's frequent exposure to earthquakes and typhoons creates significant volatility for domestic insurers. By acquiring Berkley Re, gains immediate access to a well-established platform and client base in the U.S. and European markets.

From 's perspective, the sale allows it to streamline operations and focus on its core insurance and other reinsurance businesses. The company called the deal an "excellent outcome for all stakeholders" and confirmed it will remain a significant client of the newly formed entity.

Market Reaction and Investor Takeaway

The market's initial reaction was mixed, reflecting the typical dynamics of a large acquisition. Shares of parent company fell in Tokyo, as investors weighed the cost and integration risks. Meanwhile, 's stock rose in pre-market trading in the U.S. as the deal unlocks value from one of its business units.