William S. Rosenstadt - SEC Form 4 Insider Trading Activity
Summary
Updated Aug 3, 2026
William S. Rosenstadt is a corporate insider tracked by InsiderAlpha. No SEC Form 4 filings recorded in the last 90 days.
Profile
William S. Rosenstadt holds the role of CEO and Chairman at Blueport Acquisition Ltd (BPAC). Rosenstadt has reported 2 insider filings with the SEC since 2025. The most recent filing was in December 2025.
| Role | CEO and Chairman, Director, 10% Owner |
|---|---|
| Notability | 50/100 |
Board memberships
- Blueport Acquisition Ltd
Reported roles
- CEO and Chairman
Trading Pattern
InsiderAlpha's records for William S. Rosenstadt go back to 2025: 1 primary Form 4 filing, an average of 0.5 per year. No transaction on record carries a Rule 10b5-1 flag - the filings look discretionary rather than pre-scheduled, which makes their timing more informative as a signal.
Career & Filing History
Every role William S. Rosenstadt 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.
- CEO and Chairman, Director, 10% Owner at Blueport Acquisition Ltd (BPAC) - 1 filing, 2025
Recent Transactions
| Date | Ticker | Company | Code | Shares | Price | Value |
|---|---|---|---|---|---|---|
| 2025-12-08 | BPAC | Blueport Acquisition Ltd | P - Open-market purchase | 197.2K | - |
Most Active Insiders Right Now
William S. Rosenstadt has no recent co-filers at the same companies, so here are the insiders with the largest open-market activity across the market in the last 90 days.
- MetLife Investment Management, LLC - $1600000.00B of FINS open-market activity in the last 90 days
- Magnetar Financial LLC - $16357.48B of CRWV open-market activity in the last 90 days
- Marianne Okland - $18.46B of STNG open-market activity in the last 90 days
- VisionWave Holdings, Inc. - $14.13B of SVRE open-market activity in the last 90 days
- Vanessa Allen Sutherland - $7.44B of PSX open-market activity in the last 90 days
- AI Alpine (Luxembourg) S.a.r.l. - $2.69B of INIO open-market activity in the last 90 days
More Notable Insiders
Other corporate insiders with significant SEC Form 4 track records on InsiderAlpha:
- Gregg Williams
- Stephen T. Wills
- WINMILL CO. INC
- Caroline Young
- Jeffrey Yu
- George Raymond Zage III
- Payam Zamani
- Mahkam Zanganeh
Frequently Asked Questions
Who is William S. Rosenstadt?
William S. Rosenstadt holds the role of CEO and Chairman at Blueport Acquisition Ltd (BPAC). Rosenstadt has reported 2 insider filings with the SEC since 2025. The most recent filing was in December 2025.…
Has William S. Rosenstadt been buying or selling stock?
Recorded transactions: 2 open-market purchases and 0 open-market sales across all tracked filings.
Where can I see all of William S. Rosenstadt'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 William S. Rosenstadt profile on InsiderAlpha for real-time alerts, AI-scored trade ideas, and full transaction history.