Form 4 for CSTL CASTLE BIOSCIENCES INC

Accepted 2026-09-16 16:20:30 ET · period of report 2026-09-14 · accession 0001628280-26-062255 · 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
MT	2026-09-16 16:20	2026-09-14+	CSTL	Juvenal Tobin W	Chief Commercial Off	S - Sale	$33.73	-6,600	58.6K	-10%	-$222.6K

Purchase Sale Sale after option exercise All abbreviations

#	Table	Security	Date	Code	A/D	Shares	Price	Owned after	Own	Exercise / expiry	Underlying	Footnotes
1	Common	Common Stock	2026-09-14	S	D	3,306	$32.32	61,878	D	—	—	(F1) This transaction was made pursuant to a Rule 10b5-1 plan adopted by the Reporting Person on May 28, 2026. (F2) This transaction was executed in multiple trades at prices ranging from $32.180 to $32.445, 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.
2	Common	Common Stock	2026-09-15	S	D	3,294	$35.14	58,584	D	—	—	(F1) This transaction was made pursuant to a Rule 10b5-1 plan adopted by the Reporting Person on May 28, 2026. (F3) This transaction was executed in multiple trades at prices ranging from $35.000 to $35.380, 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.