Form 4 for SPTX Seaport Therapeutics, Inc.
Accepted 2026-05-04 18:02:53 ET · period of report 2026-05-04 · accession 0001193125-26-204458 · SEC index · Original document
Summary rows
Aggregated the way they appear in lists: one row per insider, transaction code and security table.
| X | Filed | Traded | Ticker | Insider | Title | Type | Price | Qty | Owned | ΔOwn | Value |
|---|---|---|---|---|---|---|---|---|---|---|---|
| DMI | 2026-05-04 18:02 | 2026-05-04 | SPTX | ARCH Venture Partners XII, LLC | 10% | C - Cnv Deriv | — | +5.19M | 5.19M | New | — |
| DI | 2026-05-04 18:02 | 2026-05-04 | SPTX | ARCH Venture Partners XII, LLC | 10% | P - Purchase | $18.00 | +1.10M | 6.29M | +21% | +$19.80M |
| DMI | 2026-05-04 18:02 | 2026-05-04 | SPTX | ARCH Venture Partners XII, LLC | 10% | C - Cnv Deriv | $0.00 | -5.19M | 0 | -100% | $0 |
Purchase Sale Sale after option exercise All abbreviations
Every reported transaction
| # | Table | Security | Date | Code | A/D | Shares | Price | Owned after | Own | Exercise / expiry | Underlying | Footnotes |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 1 | Common | Common Stock | 2026-05-04 | C | A | 2,513,686 | — | 2,513,686 | I By ARCH Venture Fund XII, L.P. | — | — | (F1) Each share of Series A-2 and Series B Preferred Stock (collectively, the "Preferred Stock") was convertible into Common Stock of the Issuer on a one-for-3.1407 basis at the option of the holder, and automatically converted upon the closing of the Issuer's initial public offering without payment of further consideration. The Preferred Stock had no expiration date. (F2) Shares held directly by ARCH Venture Fund XII, L.P. ("ARCH XII"). ARCH Venture Partners XII, L.P. ("AVP XII LP") is the sole general partner of ARCH XII. ARCH Venture Partners XII, LLC ("AVP XII LLC") is the sole general partner of AVP XII LP. Keith Crandell, Kristina Burow, Steven Gillis and Robert Nelsen are members of the investment committee of AVP XII LLC (the "AVP XII LLC Committee Members"). Each of AVP XII LP and AVP XII LLC may be deemed to beneficially own the shares held by ARCH XII, and each of the AVP XII LLC Committee Members may be deemed to share the power to direct the disposition and vote of the shares held by ARCH XII. Each of AVP XII LP, AVP XII LLC and the AVP XII LLC Committee Members disclaims beneficial ownership except to the extent of their pecuniary interest therein, if any. |
| 2 | Common | Common Stock | 2026-05-04 | C | A | 2,681,265 | — | 5,194,951 | I By ARCH Venture Fund XII, L.P. | — | — | (F1) Each share of Series A-2 and Series B Preferred Stock (collectively, the "Preferred Stock") was convertible into Common Stock of the Issuer on a one-for-3.1407 basis at the option of the holder, and automatically converted upon the closing of the Issuer's initial public offering without payment of further consideration. The Preferred Stock had no expiration date. (F2) Shares held directly by ARCH Venture Fund XII, L.P. ("ARCH XII"). ARCH Venture Partners XII, L.P. ("AVP XII LP") is the sole general partner of ARCH XII. ARCH Venture Partners XII, LLC ("AVP XII LLC") is the sole general partner of AVP XII LP. Keith Crandell, Kristina Burow, Steven Gillis and Robert Nelsen are members of the investment committee of AVP XII LLC (the "AVP XII LLC Committee Members"). Each of AVP XII LP and AVP XII LLC may be deemed to beneficially own the shares held by ARCH XII, and each of the AVP XII LLC Committee Members may be deemed to share the power to direct the disposition and vote of the shares held by ARCH XII. Each of AVP XII LP, AVP XII LLC and the AVP XII LLC Committee Members disclaims beneficial ownership except to the extent of their pecuniary interest therein, if any. |
| 3 | Common | Common Stock | 2026-05-04 | P | A | 1,100,000 | $18.00 | 6,294,951 | I By ARCH Venture Fund XII, L.P. | — | — | (F2) Shares held directly by ARCH Venture Fund XII, L.P. ("ARCH XII"). ARCH Venture Partners XII, L.P. ("AVP XII LP") is the sole general partner of ARCH XII. ARCH Venture Partners XII, LLC ("AVP XII LLC") is the sole general partner of AVP XII LP. Keith Crandell, Kristina Burow, Steven Gillis and Robert Nelsen are members of the investment committee of AVP XII LLC (the "AVP XII LLC Committee Members"). Each of AVP XII LP and AVP XII LLC may be deemed to beneficially own the shares held by ARCH XII, and each of the AVP XII LLC Committee Members may be deemed to share the power to direct the disposition and vote of the shares held by ARCH XII. Each of AVP XII LP, AVP XII LLC and the AVP XII LLC Committee Members disclaims beneficial ownership except to the extent of their pecuniary interest therein, if any. |
| 4 | Derivative | Series A-2 Preferred Stock | 2026-05-04 | C | D | 2,513,686 | $0.00 | 0 | I By ARCH Venture Fund XII, L.P. | — · — to — | 2,513,686 Common Stock | (F1) Each share of Series A-2 and Series B Preferred Stock (collectively, the "Preferred Stock") was convertible into Common Stock of the Issuer on a one-for-3.1407 basis at the option of the holder, and automatically converted upon the closing of the Issuer's initial public offering without payment of further consideration. The Preferred Stock had no expiration date. (F1) Each share of Series A-2 and Series B Preferred Stock (collectively, the "Preferred Stock") was convertible into Common Stock of the Issuer on a one-for-3.1407 basis at the option of the holder, and automatically converted upon the closing of the Issuer's initial public offering without payment of further consideration. The Preferred Stock had no expiration date. (F1) Each share of Series A-2 and Series B Preferred Stock (collectively, the "Preferred Stock") was convertible into Common Stock of the Issuer on a one-for-3.1407 basis at the option of the holder, and automatically converted upon the closing of the Issuer's initial public offering without payment of further consideration. The Preferred Stock had no expiration date. (F2) Shares held directly by ARCH Venture Fund XII, L.P. ("ARCH XII"). ARCH Venture Partners XII, L.P. ("AVP XII LP") is the sole general partner of ARCH XII. ARCH Venture Partners XII, LLC ("AVP XII LLC") is the sole general partner of AVP XII LP. Keith Crandell, Kristina Burow, Steven Gillis and Robert Nelsen are members of the investment committee of AVP XII LLC (the "AVP XII LLC Committee Members"). Each of AVP XII LP and AVP XII LLC may be deemed to beneficially own the shares held by ARCH XII, and each of the AVP XII LLC Committee Members may be deemed to share the power to direct the disposition and vote of the shares held by ARCH XII. Each of AVP XII LP, AVP XII LLC and the AVP XII LLC Committee Members disclaims beneficial ownership except to the extent of their pecuniary interest therein, if any. |
| 5 | Derivative | Series B Preferred Stock | 2026-05-04 | C | D | 2,681,265 | $0.00 | 0 | I By ARCH Venture Fund XII, L.P. | — · — to — | 2,681,265 Common Stock | (F1) Each share of Series A-2 and Series B Preferred Stock (collectively, the "Preferred Stock") was convertible into Common Stock of the Issuer on a one-for-3.1407 basis at the option of the holder, and automatically converted upon the closing of the Issuer's initial public offering without payment of further consideration. The Preferred Stock had no expiration date. (F1) Each share of Series A-2 and Series B Preferred Stock (collectively, the "Preferred Stock") was convertible into Common Stock of the Issuer on a one-for-3.1407 basis at the option of the holder, and automatically converted upon the closing of the Issuer's initial public offering without payment of further consideration. The Preferred Stock had no expiration date. (F1) Each share of Series A-2 and Series B Preferred Stock (collectively, the "Preferred Stock") was convertible into Common Stock of the Issuer on a one-for-3.1407 basis at the option of the holder, and automatically converted upon the closing of the Issuer's initial public offering without payment of further consideration. The Preferred Stock had no expiration date. (F2) Shares held directly by ARCH Venture Fund XII, L.P. ("ARCH XII"). ARCH Venture Partners XII, L.P. ("AVP XII LP") is the sole general partner of ARCH XII. ARCH Venture Partners XII, LLC ("AVP XII LLC") is the sole general partner of AVP XII LP. Keith Crandell, Kristina Burow, Steven Gillis and Robert Nelsen are members of the investment committee of AVP XII LLC (the "AVP XII LLC Committee Members"). Each of AVP XII LP and AVP XII LLC may be deemed to beneficially own the shares held by ARCH XII, and each of the AVP XII LLC Committee Members may be deemed to share the power to direct the disposition and vote of the shares held by ARCH XII. Each of AVP XII LP, AVP XII LLC and the AVP XII LLC Committee Members disclaims beneficial ownership except to the extent of their pecuniary interest therein, if any. |