Insiders who reported open-market trades in the last 12 months at the companies Michael J. O'Sullivan files at. Multiple unrelated insiders buying the same stock within a short window, cluster buying, has historically been one of the strongest Form 4 signals.
Ajit Jain - $19.97M in BRK.A purchases and sales in the last 12 months
Gregory E. Abel - $15.31M in BRK.A purchases and sales in the last 12 months
Charles C. Chang - $1.53M in BRK.A purchases and sales in the last 12 months
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Michael J. O'Sullivan is a corporate insider, tracked as Senior Vice President, General Counsel and Secretary of BERKSHIRE HATHAWAY INC (BRK.A). InsiderAlpha holds 15 primary Form 4 filings for them, the earliest from 2024, updated as new SEC EDGAR filings are processed.
How many SEC Form 4 filings has Michael J. O'Sullivan submitted recently?
1 primary Form 4 filing in the last 90 days, covering 1 company.
Has Michael J. O'Sullivan been buying or selling stock?
Recorded transactions: 5 open-market purchases ($501K) and 13 open-market sales ($3.59M) across all tracked filings.
Michael J. O'Sullivan is Senior Vice President, General Counsel and Secretary of BERKSHIRE HATHAWAY INC (BRK.A). 15 SEC Form 4 filings on record going back to 2024, most recently on 13 August 2026. Most recent open-market trade: bought $22K of BRK.A on 13 August 2026. Lifetime open-market purchases: $501K. Lifetime open-market sales: $3.59M.
Recent transactions
20
The latest 20 SEC Form 4 transactions reported by Michael J. O'Sullivan.
InsiderAlpha's records for Michael J. O'Sullivan go back to 2024: 15 primary Form 4 filings, an average of 5.0 per year. The typical open-market purchase is $100K (5 buys totaling $501K). The largest single buy on record is $226K of BRK.A in 2026. Sales side: 13 recorded sales totaling $3.59M, so the filing history runs sell-heavy by dollar value. 4 recorded transactions carry a Rule 10b5-1 plan flag. This identifies the marked transactions as reported under a trading plan; it does not establish the plan status of unmarked transactions.
