MITSUI SUMITOMO INSURANCE CO LTD 4

What Happened
Mitsui Sumitomo Insurance Co., Ltd. (MSI), a reported 10% owner of W.R. Berkley Corporation (WRB), purchased a total of 97,996 WRB shares in multiple open‑market transactions from Feb 9–11, 2026. The purchases were effected under a Rule 10b5‑1 trading plan adopted Oct 3, 2025. Transaction details:

• 2026-02-09 — 35,952 shares @ $69.27 each = $2,490,553 (weighted avg; multiple executions)
• 2026-02-09 — 4,048 shares @ $70.32 each = $284,653 (weighted avg)
• 2026-02-10 — 21,884 shares @ $69.09 each = $1,511,904 (weighted avg)
• 2026-02-10 — 12,082 shares @ $69.92 each = $844,787 (weighted avg)
• 2026-02-11 — 9,289 shares @ $69.59 each = $646,400 (weighted avg)
• 2026-02-11 — 3,578 shares @ $70.50 each = $252,266 (weighted avg)
• 2026-02-11 — 11,163 shares @ $71.45 each = $797,589 (weighted avg)
  Total purchased: 97,996 shares for approximately $6.83 million. Purchases are generally viewed as a positive signal (institutional buying) but do not on their own prove intent.

Key Details

• Dates: Feb 9–11, 2026 (Form filed Feb 11, 2026; appears timely).
• Price info: Reported prices are weighted averages; execution price ranges per footnotes:
  • 02/09 (35,952): $69.0015–$69.9972
  • 02/09 (4,048): $70.0059–$70.925
  • 02/10 (21,884): $68.53–$69.505
  • 02/10 (12,082): $69.5057–$70.185
  • 02/11 (9,289): $69.28–$69.9981
  • 02/11 (3,578): $70.00–$70.9925
  • 02/11 (11,163): $71.0043–$71.635
• Shares owned after transaction: not specified in the provided Form 4 excerpt.
• Notable footnotes: purchases were made under a 10b5‑1 plan (F1); MSI holds the shares directly but is a wholly‑owned subsidiary of MS&AD (F3) — MS&AD may be deemed to beneficially own them but disclaims such ownership except for pecuniary interest; weighted‑average pricing and execution ranges described in footnotes (F2–F9).
• Remarks: MSI, the issuer and WR Berkley & Others LLC have certain agreements (see Schedule 13D); MSI disclaims group status with WRBO.

Context

• This is institutional buying by a reported 10% owner, not an executive/officer trade — different implications than insider executive activity.
• The 10b5‑1 plan means trades were pre‑scheduled, which can reduce the likelihood trades were timed on inside information but still represent material purchases by a large holder.
• No options, awards, gifts, or tax‑withholding events are reported in this filing.