Brian J. Costanzo
CIK 1873434 · Chief Financial Officer · last filed 2026-05-19
Brian J. Costanzo is a Chief Financial Officer who has filed 24 SEC Form 4 insider transactions across 1 company since 2022. The most recent filing, for MKL, was dated May 19, 2026. Current disclosed insider exposure totals $3.4M across reported positions.
"Disclosed insider exposure" sums this person's most-recently-reported share counts across each company they're an insider in, multiplied by the current underlying price. It is not net worth — it misses retail holdings, private investments, real estate, index funds, and any company where the person isn't an SEC-reporting insider. For informational purposes only.
$3.37M
1
24
$0
Holdings By Company
| Symbol | Role | Shares | Price | Disclosed Exposure | Lifetime OM Net | Filings | Latest Filed |
|---|---|---|---|---|---|---|---|
| MKL | Chief Financial Officer | 1,826 | $1846.00 | $3.37M | $0 | 24 | 2026-05-19 |
Recent Filings
24 filings| Filed | Symbol | Action | Net Shares | Net $ | Link |
|---|---|---|---|---|---|
| 2026-05-19 | MKL | Mixed | +17 | $25.9K | EDGAR |
| 2026-04-15 | MKL | Other (J) | +1 | $3.0K | EDGAR |
| 2026-02-26 | MKL | Grant (A) | +654 | $0 | EDGAR |
| 2026-01-20 | MKL | Other (J) | +2 | $3.5K | EDGAR |
| 2025-12-03 | MKL | Tax (F) | −21 | -$44.8K | EDGAR |
| 2025-10-16 | MKL | Other (J) | +1 | $3.0K | EDGAR |
| 2025-07-16 | MKL | Other (J) | +2 | $3.5K | EDGAR |
| 2025-04-17 | MKL | Other (J) | +2 | $3.0K | EDGAR |
| 2025-02-20 | MKL | Grant (A) | +379 | $0 | EDGAR |
| 2025-01-17 | MKL | Other (J) | +2 | $2.8K | EDGAR |