ARCH Venture Partners XII, LLC bought $20M of SPTX
owner at Seaport Therapeutics, Inc.. 1,100,000 shares at an average of $18.00, traded May 4, 2026, filed May 4, 2026.
Score components
- +12Role10% owner
- +25Trade size$19.8M at market
- +6Relative to holdingsHoldings up 21%
- 0Price contextNo price history yet
- 0ClusterNo other insider buying within 14 days
- 0Repeat buyingFirst buy in 90 days
- 0Track recordToo few past buys to judge (0 with prices)
- -5Outside holderA 10% owner who is not an officer or director
What happened after comparable buys
Same side and tier, against the S&P 500, at 1, 3 and 6 months. Shown to Pro users; the whole table is on the backtest page.
This signal so far: 1m +1.4%, 3m +21.5%, 6m -.
Price around the trade, and since
From a quarter before the trade to today. The arrow is the trade, the circle the day the filing reached EDGAR, which is the first day anyone outside could act; the dotted line is the S&P 500 rebased to that day's close.
Daily candles, adjusted for splits and dividends. Green arrows are insider buys, red are sells, sized by value; the dashed line is the close on the filing day, the dotted line SPY rebased to it.Charts by TradingView Lightweight Charts™
Rows in this filing
Every transaction in Form 4 0001193125-26-204458, as filed. Open on EDGAR
| Date | Transaction | Shares | Price | Value | Holdings after | Filed |
|---|---|---|---|---|---|---|
| May 4, 2026 | CConversion Common Stockindirect: By ARCH Venture Fund XII, L.P. | +2,513,686 | - | - | 2,513,686 | May 4, 2026 |
| May 4, 2026 | CConversion Common Stockindirect: By ARCH Venture Fund XII, L.P. | +2,681,265 | - | - | 5,194,951 | May 4, 2026 |
| May 4, 2026 | POpen-market purchase Common Stockindirect: By ARCH Venture Fund XII, L.P. | +1,100,000 | $18.00 | $20M | 6,294,951 | May 4, 2026 |
| May 4, 2026 | CConversion Series A-2 Preferred Stockderivativeindirect: By ARCH Venture Fund XII, L.P. | -2,513,686 | $0.00 | $0 | 0 | May 4, 2026 |
| May 4, 2026 | CConversion Series B Preferred Stockderivativeindirect: By ARCH Venture Fund XII, L.P. | -2,681,265 | $0.00 | $0 | 0 | May 4, 2026 |
Related signals
Other insiders at Seaport Therapeutics, Inc. and this insider’s other filings.
| Score | Company | Insider | Value | Holdings | Filed |
|---|---|---|---|---|---|
| 36Weak | SPTXbuy Seaport Therapeutics, Inc. | Robert J. Hombach director | $236k 13,000 shares | - |
Not investment advice. Scores and forward returns are decision support built from public SEC filings and past prices; they describe what happened after comparable filings, not what will happen after this one. Do your own research and size your risk.