Form 4 for CSTL CASTLE BIOSCIENCES INC
Accepted 2026-06-03 16:15:50 ET · period of report 2026-06-01 · accession 0001628280-26-040260 · 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 | 2026-06-03 16:15 | 2026-06-01 | CSTL | MAETZOLD DEREK J | Pres, Chief Exec. Off, Dir | M - OptEx | $2.39 | +6,214 | 27.7K | +29% | +$14.9K |
| DT | 2026-06-03 16:15 | 2026-06-01 | CSTL | MAETZOLD DEREK J | Pres, Chief Exec. Off, Dir | S - Sale+OE | $20.86 | -6,214 | 21.5K | -22% | -$129.6K |
| DMTI | 2026-06-03 16:15 | 2026-06-01 | CSTL | MAETZOLD DEREK J | Pres, Chief Exec. Off, Dir | S - Sale+OE | $20.86 | -3,622 | 1,668 | -68% | -$75.5K |
| DMT | 2026-06-03 16:15 | 2026-06-01 | CSTL | MAETZOLD DEREK J | Pres, Chief Exec. Off, Dir | M - OptEx | $0.00 | -6,214 | 92.4K | -6% | $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 | 2026-06-01 | M | A | 204 | $2.39 | 21,683 | D | — | — | (F1) These transactions were made pursuant to a Rule 10b5-1 plan adopted by the Reporting Person on December 3, 2025. |
| 2 | Common | Common Stock | 2026-06-01 | M | A | 6,010 | $2.39 | 27,693 | D | — | — | (F1) These transactions were made pursuant to a Rule 10b5-1 plan adopted by the Reporting Person on December 3, 2025. |
| 3 | Common | Common Stock | 2026-06-01 | S | D | 6,214 | $20.86 | 21,479 | D | — | — | (F1) These transactions were made pursuant to a Rule 10b5-1 plan adopted by the Reporting Person on December 3, 2025. (F2) This transaction was executed in multiple trades at prices ranging from $20.470 to $21.175, 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. |
| 4 | Common | Common Stock | 2026-06-01 | S | D | 1,357 | $20.86 | 43,424 | 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. (F2) This transaction was executed in multiple trades at prices ranging from $20.470 to $21.175, 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. (F3) 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. |
| 5 | Common | Common Stock | 2026-06-01 | S | D | 1,153 | $20.86 | 36,908 | 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. (F2) This transaction was executed in multiple trades at prices ranging from $20.470 to $21.175, 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 Derek Maetzold 2020 Irrevocable Trust of which the Reporting Person is the trustee and his children are beneficiaries. |
| 6 | Common | Common Stock | 2026-06-01 | S | D | 278 | $20.86 | 1,668 | I By The Maetzold 2018 Remainder Trust FBO Emily Carol Kirk | — | — | (F1) These transactions were made pursuant to a Rule 10b5-1 plan adopted by the Reporting Person on December 3, 2025. (F2) This transaction was executed in multiple trades at prices ranging from $20.470 to $21.175, 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 The Maetzold 2018 Remainder Trust FBO Emily Carol Kirk of which the Reporting Person is the trustee and his child is the beneficiary. |
| 7 | Common | Common Stock | 2026-06-01 | S | D | 278 | $20.86 | 1,668 | I By The Maetzold 2018 Remainder Trust FBO Hannah Elizabeth Maetzold | — | — | (F1) These transactions were made pursuant to a Rule 10b5-1 plan adopted by the Reporting Person on December 3, 2025. (F2) This transaction was executed in multiple trades at prices ranging from $20.470 to $21.175, 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. (F6) Held by The Maetzold 2018 Remainder Trust FBO Hannah Elizabeth Maetzold of which the Reporting Person is the trustee and his child is the beneficiary. |
| 8 | Common | Common Stock | 2026-06-01 | S | D | 278 | $20.86 | 1,668 | I By The Maetzold 2018 Remainder Trust FBO John Derek Maetzold | — | — | (F1) These transactions were made pursuant to a Rule 10b5-1 plan adopted by the Reporting Person on December 3, 2025. (F2) This transaction was executed in multiple trades at prices ranging from $20.470 to $21.175, 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. (F7) Held by The Maetzold 2018 Remainder Trust FBO John Derek Maetzold of which the Reporting Person is the trustee and his child is the beneficiary. |
| 9 | Common | Common Stock | 2026-06-01 | S | D | 278 | $20.86 | 1,668 | I By The Maetzold 2018 Remainder Trust FBO Peter Douglas Maetzold | — | — | (F1) These transactions were made pursuant to a Rule 10b5-1 plan adopted by the Reporting Person on December 3, 2025. (F2) This transaction was executed in multiple trades at prices ranging from $20.470 to $21.175, 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. (F8) Held by The Maetzold 2018 Remainder Trust FBO Peter Douglas Maetzold of which the Reporting Person is the trustee and his child is the beneficiary. |
| 10 | Derivative | Stock option (right to buy) | 2026-06-01 | M | D | 204 | $0.00 | 0 | D | $2.39 · — to 2028-11-11 | 204 Common Stock | (F1) These transactions were made pursuant to a Rule 10b5-1 plan adopted by the Reporting Person on December 3, 2025. (F12) The shares subject to the option are fully vested. |
| 11 | Derivative | Stock option (right to buy) | 2026-06-01 | M | D | 6,010 | $0.00 | 92,431 | D | $2.39 · — to 2028-05-09 | 6,010 Common Stock | (F1) These transactions were made pursuant to a Rule 10b5-1 plan adopted by the Reporting Person on December 3, 2025. (F12) The shares subject to the option are fully vested. |