Form 4 for CSTL CASTLE BIOSCIENCES INC
Accepted 2026-08-04 16:35:54 ET · period of report 2026-07-31 · accession 0001628280-26-052647 · 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 |
|---|---|---|---|---|---|---|---|---|---|---|---|
| DMT | 2026-08-04 16:35 | 2026-07-31+ | CSTL | MAETZOLD DEREK J | Pres, Chief Exec. Off, Dir | M - OptEx | $2.39 | +17.1K | 32.1K | +114% | +$41.0K |
| DMT | 2026-08-04 16:35 | 2026-07-31+ | CSTL | MAETZOLD DEREK J | Pres, Chief Exec. Off, Dir | S - Sale+OE | $30.28 | -17.1K | 21.5K | -44% | -$519.1K |
| DMTI | 2026-08-04 16:35 | 2026-07-31+ | CSTL | MAETZOLD DEREK J | Pres, Chief Exec. Off, Dir | S - Sale+OE | $30.29 | -11.5K | 27.0K | -30% | -$348.4K |
| DMT | 2026-08-04 16:35 | 2026-07-31+ | CSTL | MAETZOLD DEREK J | Pres, Chief Exec. Off, Dir | M - OptEx | $0.00 | -17.1K | 61.8K | -22% | $0 |
Every reported transaction
| # | Table | Security | Date | Code | A/D | Shares | Price | Owned after | Own | Exercise / expiry | Underlying | Footnotes |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 1 | Common | Common Stock | 2026-07-31 | M | A | 6,480 | $2.39 | 27,959 | D | — | — | (F1) These transactions were made pursuant to a Rule 10b5-1 plan adopted by the Reporting Person on December 3, 2025. (F2) Reflects the July 30, 2026 transfers of 6,755 shares of common stock from DJM Grantor Retained Annuity Trust No. 6 and 16,461 shares from DJM Grantor Retained Annuity Trust No. 7 to the Reporting Person's direct holdings, followed by the transfer of those shares to DJM Grantor Retained Annuity Trust No. 9. |
| 2 | Common | Common Stock | 2026-07-31 | S | D | 6,480 | $30.15 | 21,479 | D | — | — | (F1) These transactions were made pursuant to a Rule 10b5-1 plan adopted by the Reporting Person on December 3, 2025. (F3) This transaction was executed in multiple trades at prices ranging from $30.000 to $30.473, inclusive. The price reported above reflects the weighted-average sale price. The Reporting Person hereby undertakes to provide upon request to the Securities and Exchange Commission staff, the issuer or a security holder of the issuer full information regarding the number of shares and prices at which the transaction was effected. |
| 3 | Common | Common Stock | 2026-07-31 | S | D | 1,983 | $30.15 | 36,013 | I By The Maetzold Descendants 2020 Trust | — | — | (F1) These transactions were made pursuant to a Rule 10b5-1 plan adopted by the Reporting Person on December 3, 2025. (F3) This transaction was executed in multiple trades at prices ranging from $30.000 to $30.473, inclusive. The price reported above reflects the weighted-average sale price. The Reporting Person hereby undertakes to provide upon request to the Securities and Exchange Commission staff, the issuer or a security holder of the issuer full information regarding the number of shares and prices at which the transaction was effected. (F4) Held by The Maetzold Descendants 2020 Trust of which the Reporting Person's spouse is the trustee and the Reporting Person's spouse and their children are beneficiaries. |
| 4 | Common | Common Stock | 2026-07-31 | S | D | 1,690 | $30.15 | 30,606 | I By Derek Maetzold 2020 Irrevocable Trust | — | — | (F1) These transactions were made pursuant to a Rule 10b5-1 plan adopted by the Reporting Person on December 3, 2025. (F3) This transaction was executed in multiple trades at prices ranging from $30.000 to $30.473, inclusive. The price reported above reflects the weighted-average sale price. The Reporting Person hereby undertakes to provide upon request to the Securities and Exchange Commission staff, the issuer or a security holder of the issuer full information regarding the number of shares and prices at which the transaction was effected. (F5) Held by Derek Maetzold 2020 Irrevocable Trust of which the Reporting Person is the trustee and his children are beneficiaries. |
| 5 | Common | Common Stock | 2026-08-03 | M | A | 10,664 | $2.39 | 32,143 | D | — | — | (F1) These transactions were made pursuant to a Rule 10b5-1 plan adopted by the Reporting Person on December 3, 2025. |
| 6 | Common | Common Stock | 2026-08-03 | S | D | 10,664 | $30.35 | 21,479 | D | — | — | (F1) These transactions were made pursuant to a Rule 10b5-1 plan adopted by the Reporting Person on December 3, 2025. (F6) This transaction was executed in multiple trades at prices ranging from $30.000 to $30.725, inclusive. The price reported above reflects the weighted-average sale price. The Reporting Person hereby undertakes to provide upon request to the Securities and Exchange Commission staff, the issuer or a security holder of the issuer full information regarding the number of shares and prices at which the transaction was effected. |
| 7 | Common | Common Stock | 2026-08-03 | S | D | 4,232 | $30.35 | 31,781 | I By The Maetzold Descendants 2020 Trust | — | — | (F1) These transactions were made pursuant to a Rule 10b5-1 plan adopted by the Reporting Person on December 3, 2025. (F6) This transaction was executed in multiple trades at prices ranging from $30.000 to $30.725, inclusive. The price reported above reflects the weighted-average sale price. The Reporting Person hereby undertakes to provide upon request to the Securities and Exchange Commission staff, the issuer or a security holder of the issuer full information regarding the number of shares and prices at which the transaction was effected. (F4) Held by The Maetzold Descendants 2020 Trust of which the Reporting Person's spouse is the trustee and the Reporting Person's spouse and their children are beneficiaries. |
| 8 | Common | Common Stock | 2026-08-03 | S | D | 3,597 | $30.35 | 27,009 | I By Derek Maetzold 2020 Irrevocable Trust | — | — | (F1) These transactions were made pursuant to a Rule 10b5-1 plan adopted by the Reporting Person on December 3, 2025. (F6) This transaction was executed in multiple trades at prices ranging from $30.000 to $30.725, inclusive. The price reported above reflects the weighted-average sale price. The Reporting Person hereby undertakes to provide upon request to the Securities and Exchange Commission staff, the issuer or a security holder of the issuer full information regarding the number of shares and prices at which the transaction was effected. (F5) Held by Derek Maetzold 2020 Irrevocable Trust of which the Reporting Person is the trustee and his children are beneficiaries. |
| 9 | Derivative | Stock option (right to buy) | 2026-07-31 | M | D | 6,480 | $0.00 | 72,423 | D | $2.39 · — to 2028-05-09 | 6,480 Common Stock | (F1) These transactions were made pursuant to a Rule 10b5-1 plan adopted by the Reporting Person on December 3, 2025. (F15) The shares subject to the option are fully vested. |
| 10 | Derivative | Stock option (right to buy) | 2026-08-03 | M | D | 10,664 | $0.00 | 61,759 | D | $2.39 · — to 2028-05-09 | 10,664 Common Stock | (F1) These transactions were made pursuant to a Rule 10b5-1 plan adopted by the Reporting Person on December 3, 2025. (F15) The shares subject to the option are fully vested. |