BOBULSKY SUSAN 4

What Happened
Susan Bobulsky, Chief Commercial Officer of Adaptive Biotechnologies (ADPT), sold 41,338 shares on 2026-03-11 at $13.17 per share, generating proceeds of $544,421. The Form 4 lists the transaction as a sale (S) and the filing was made on 2026-03-13.

Key Details

• Transaction date & price: 2026-03-11, 41,338 shares @ $13.17 each (total $544,421)
• Transaction type: Sale (reported as open market/private sale) with footnote indicating a "sell-to-cover" for tax withholding (see below)
• Footnote: F1 — Shares were sold to satisfy tax withholding obligations on vested RSUs; this was a mandated sell-to-cover, not a discretionary trade by the reporting person
• Shares owned after transaction: Not disclosed in the provided excerpt of the filing
• Filing timeliness: Reported on 2026-03-13 for a 2026-03-11 transaction — appears to be timely

Context
Sell-to-cover transactions occur when an issuer's equity plan requires withholding taxes on RSU vesting to be satisfied by selling a portion of the vested shares. These mandatory sales are routine and generally do not signal a change in the insider's view of the company. Purchases by insiders typically carry more weight for signaling than routine tax-withholding sales.