Michael J. O'Sullivan - SEC Form 4 Insider Trading Activity
Summary
Updated Aug 3, 2026
Michael J. O'Sullivan has filed 1 SEC Form 4 filing across 1 company in the last 90 days - active on both sides. Lifetime open-market purchases: $251K. Lifetime open-market sales: $3.59M.
Profile
Michael J. O'Sullivan is a corporate insider at BERKSHIRE HATHAWAY INC (BRK.A). SEC records also connect O'Sullivan to Snap Inc (SNAP). O'Sullivan has reported 18 insider filings with the SEC since 2024. The most recent filing was in May 2026.
| Role | Senior Vice President, General Counsel and Secretary |
|---|---|
| Notability | 20/100 |
Board memberships
- BERKSHIRE HATHAWAY INC
- Snap Inc
Awards & honors
- Listed in SEC insider filings related to Snap Inc and Berkshire Hathaway Inc as of 2026-05-06
Trading Pattern
InsiderAlpha's records for Michael J. O'Sullivan go back to 2024: 14 primary Form 4 filings, an average of 4.7 per year. The typical open-market purchase is $125K (2 buys totaling $251K). 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 flag, meaning they were pre-scheduled under a written trading plan rather than discretionary.
Career & Filing History
Every role Michael J. O'Sullivan has reported on a Form 4, reconstructed from the filings themselves - reporting insiders must state their relationship to the issuer (officer title, director seat, or 10% ownership) on every filing.
- Insider at BERKSHIRE HATHAWAY INC (BRK.A) - 1 filing, 2026
- General Counsel at Snap Inc (SNAP) - 13 filings, 2024 to 2025
Recent Transactions
| Date | Ticker | Company | Code | Shares | Price | Value |
|---|---|---|---|---|---|---|
| 2026-05-06 | BRK.A | BERKSHIRE HATHAWAY INC | P - Open-market purchase | 53 | $470.22 | $25K |
| 2026-05-06 | BRK.A | BERKSHIRE HATHAWAY INC | P - Open-market purchase | 483 | $467.13 | $226K |
| 2025-11-19 | SNAP | Snap Inc | J - Other acquisition / disposition | 60.1K | $0.00 | |
| 2025-11-19 | SNAP | Snap Inc | J - Other acquisition / disposition | 60.1K | $0.00 | |
| 2025-11-19 | SNAP | Snap Inc | S - Open-market sale | 70.9K | $8.34 | $591K |
| 2025-11-04 | SNAP | Snap Inc | S - Open-market sale [10b5-1] | 24.0K | $7.73 | $186K |
| 2025-09-30 | SNAP | Snap Inc | S - Open-market sale | 24.0K | $7.86 | $189K |
| 2025-09-16 | SNAP | Snap Inc | J - Other acquisition / disposition | 13.2K | $0.00 | |
| 2025-09-16 | SNAP | Snap Inc | J - Other acquisition / disposition | 13.2K | $0.00 | |
| 2025-09-16 | SNAP | Snap Inc | S - Open-market sale | 14.3K | $7.58 | $108K |
| 2025-08-29 | SNAP | Snap Inc | S - Open-market sale | 24.0K | $7.16 | $172K |
| 2025-08-18 | SNAP | Snap Inc | J - Other acquisition / disposition | 62.3K | $0.00 | |
| 2025-08-18 | SNAP | Snap Inc | J - Other acquisition / disposition | 62.3K | $0.00 | |
| 2025-08-18 | SNAP | Snap Inc | S - Open-market sale | 68.7K | $7.18 | $493K |
| 2025-07-31 | SNAP | Snap Inc | S - Open-market sale | 24.0K | $9.57 | $230K |
| 2025-06-30 | SNAP | Snap Inc | S - Open-market sale | 24.0K | $8.71 | $209K |
| 2024-12-18 | SNAP | Snap Inc | J - Other acquisition / disposition | 52.5K | $0.00 | |
| 2024-12-18 | SNAP | Snap Inc | J - Other acquisition / disposition | 52.5K | $0.00 | |
| 2024-12-18 | SNAP | Snap Inc | S - Open-market sale | 57.0K | $11.44 | $652K |
| 2024-12-03 | SNAP | Snap Inc | S - Open-market sale [10b5-1] | 18.0K | $11.89 | $214K |
Companies - Last 90 Days
- BERKSHIRE HATHAWAY INC (BRK.A) - 1 filing, last 2026-05-06
Other Insiders Active in the Same Stocks
Insiders who reported open-market trades at the companies Michael J. O'Sullivan has recently filed at. Multiple unrelated insiders buying the same stock within a short window - cluster buying - has historically been one of the strongest Form 4 signals.
- Gregory E. Abel - $15.31M of BRK.A open-market activity in the last 12 months
- Ajit Jain - $929K of BRK.A open-market activity in the last 12 months
More Notable Insiders
Other corporate insiders with significant SEC Form 4 track records on InsiderAlpha:
- Andrew J. Mills
- Charles N. Mills
- Kevin J. Mills
- Mink Brook Asset Management LLC
- Shankh Mitra
- MITSUI SUMITOMO INSURANCE CO LTD
- Arturo R. Moreno
- Matthew T. Moroun
Frequently Asked Questions
Who is Michael J. O'Sullivan?
Michael J. O'Sullivan is a corporate insider at BERKSHIRE HATHAWAY INC (BRK.A). SEC records also connect O'Sullivan to Snap Inc (SNAP). O'Sullivan has reported 18 insider filings with the SEC since 2024. The most recent filing was in May 2026.…
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: 2 open-market purchases ($251K) and 13 open-market sales ($3.59M) across all tracked filings.
Where can I see all of Michael J. O'Sullivan's SEC filings?
All Form 4 filings, transaction values, and 10b5-1 plan flags are listed on this page and updated in real time as new SEC EDGAR filings are processed.
Learn More
Open the live Michael J. O'Sullivan profile on InsiderAlpha for real-time alerts, AI-scored trade ideas, and full transaction history.