MITSUI SUMITOMO INSURANCE CO LTD 4

What Happened

• Mitsui Sumitomo Insurance Co., Ltd. (MSI) — a reported 10% owner — purchased a total of 630,000 shares of W.R. Berkley Corporation (WRB) on Jan 20–21, 2026. The four reported lots: 265,006 @ $67.75 ($17,954,316), 44,994 @ $68.08 ($3,063,066), 59,002 @ $66.95 ($3,950,337), and 260,998 @ $67.60 ($17,644,300), totaling approximately $42.61 million.
• MS&AD Insurance Group Holdings, Inc. (the parent) filed a corresponding Form 4 reporting the same acquisitions (MS&AD may be deemed to beneficially own the shares because MSI is its wholly owned subsidiary, though MS&AD disclaims beneficial ownership except for any pecuniary interest). These are purchases (buying stock), not sales.

Key Details

• Transaction dates: Jan 20, 2026 and Jan 21, 2026.
• Transaction type: Open-market purchases (code P). Total per reporting person: 630,000 shares, ~$42.612M.
• Price details: Reported as weighted averages; underlying trades ranged roughly from $66.5523 to $68.2013 per share (per filing footnotes).
• Plan/authorization: Purchases were effected under a Rule 10b5-1 trading plan adopted Oct 3, 2025 (footnote F1).
• Shares owned after transaction: Not specified in the details you provided.
• Filing timeliness: Report filed Jan 21, 2026 for trades on Jan 20–21, 2026 (appears timely).
• Other notes: The filing references prior agreements among MSI, the issuer and WR Berkley & Others LLC (see the Schedule 13D filed Dec 11, 2025); MS&AD disclaims group status with WRBO.

Context

• These are institutional purchases by a reported 10% owner and its parent, executed pursuant to a pre-established 10b5-1 plan — a common mechanism for scheduled insider purchases that limits inference about timing or intent.
• For retail investors: purchases by a large, long-term institutional holder can be viewed as a material insider buy, but the 10b5-1 plan and the parent/subsidiary reporting nuance mean this is institutional rebalancing under a pre-set plan rather than an ad hoc insider signal.