Japan-based insurer Mitsui Sumitomo Insurance (MSI) has acquired beneficial ownership of at least 12.5% of American insurer W. R. Berkley Corporation's (WRB) outstanding common stock, according to a WRB press release dated 5 December 2025.
MSI obtained the shares through prior arrangements with a company controlled by the Berkley family and associated trusts, with none of the shares being purchased directly from W. R. Berkley Corporation or the family.
Under the agreements, the Berkley family, the founding family and principal shareholders of the US firm, will generally provide voting guidance for MSI’s shares, except in certain limited circumstances where the MSI shares will be voted in proportion to how all other non-MSI shares are cast.
MSI is expected to complete the investment under the agreements in the first quarter of 2026.