Rambus CEO Luc Seraphin Has Sold $21M in RMBS Stock — 10,000 Shares Per Week Like Clockwork
Rambus CEO Luc Seraphin has sold $21M across 133 transactions with a clockwork pattern: 10,000 shares every week in April 2025 at $45-$59/share, while maintaining a 319K-share position.
Luc Seraphin, President and CEO of Rambus Inc (RMBS), has sold $21 million in company stock across 133 transactions with zero career purchases. His April 2025 selling pattern was mechanical precision: exactly 10,000 shares sold every Tuesday for five consecutive weeks at prices ranging from $45 to $59.
The Numbers
| Metric | Value |
|---|---|
| Career Sell Value | $21.0M |
| Career Buy Value | $0 |
| Total Transactions | 133 |
| Last Transaction | 2026-02-01 |
| Shares Remaining | 319,241 |
Recent Activity
| Date | Type | Shares | Price | Est. Value |
|---|---|---|---|---|
| 2025-04-23 | Sell | 6,348 | $46.9700 | $298K |
| 2025-04-22 | Sell | 1,255 | $45.0000 | $56K |
| 2025-04-15 | Sell | 10,000 | $47.7868 | $478K |
| 2025-04-08 | Sell | 10,000 | $46.8100 | $468K |
| 2025-04-01 | Sell | 10,000 | $50.8815 | $509K |
The weekly 10,000-share cadence is the clearest 10b5-1 plan signature in Seraphin's filing history. Each sale occurred on a Tuesday, suggesting a predetermined execution schedule. The price decline from $58.64 (March 25) to $45.00 (April 22) during the selling window means his plan executed through a 23% price drop without interruption — confirming these were automatic, not discretionary trades.
What It Means
Seraphin's selling profile is a textbook 10b5-1 plan in action. The identical lot sizes (10,000 shares), consistent day-of-week execution (Tuesdays), and continuation through adverse price moves all point to a pre-set disposition program. For Rambus investors, this pattern is actually the least alarming form of insider selling — it signals planned diversification, not discretionary timing.
With 319,241 shares remaining (~$15M at recent prices), Seraphin maintains a substantial personal stake in Rambus. The company's pivot from patent licensing to silicon IP for data centers and AI infrastructure has positioned RMBS as a semiconductor picks-and-shovels play. A CEO who sells mechanically while retaining 15x his annual selling rate in shares is managing personal risk, not abandoning the company thesis.
What to Watch
- Whether Seraphin's 10b5-1 plan resumes in 2026 after the April 2025 selling window
- Rambus's HBM and chiplet interface technology revenue trajectory
- Memory industry CapEx trends driving demand for Rambus silicon IP
- Any plan amendments that change the lot size or frequency of sales
Breaking News Editor at 13F Insight. First to report on major SEC filings, institutional moves, and regulatory developments.
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