Sutro Biopharma (STRO) CSO Hans-Peter Gerber Receives RSUs

What Happened
Hans-Peter Gerber, Chief Scientific Officer of Sutro Biopharma (STRO), had 3,750 restricted stock units (RSUs convert to common shares) vest on 2026-09-18. All 3,750 RSUs converted to common stock; the issuer withheld 1,345 shares to satisfy tax withholding (reported value $15.34/share, withholding = $20,632). Based on the $15.34 price, the gross value of the vested shares was about $57,525 and Gerber’s net increase in common shares was 2,405 (3,750 vested − 1,345 withheld). This was an award/vesting event, not an open-market purchase or sale.

Key Details

• Transaction date: 2026-09-18 (reported on Form 4 filed 2026-09-22).
• Transactions reported:
  • 3,750 RSUs converted to common stock (transaction code M).
  • 1,345 shares withheld to satisfy tax withholding (transaction code F) at $15.34/share = $20,632.
  • The filing also lists the conversion/disposition of the derivative RSUs as part of the vesting mechanics.
• Net new shares to insider: +2,405 shares.
• Footnotes of note:
  • F1: 444 shares included in the reported total were acquired under the company ESPP and are exempt under specified rules.
  • F2: Withheld shares represent tax withholding to satisfy employer obligations and do not represent a market sale by the reporting person.
  • F3/F4: Each RSU equals one share on settlement; the awards vest 1/4 annually with the first tranche on 9/18/2024 (subject to continued service).
• Shares owned after transaction: not provided in the excerpted data.

Context
This is a routine RSU vesting and net-settlement for tax withholding (issuer withheld shares rather than an open-market sale). Such transactions reflect compensation being converted into stock rather than a discretionary buy or sell by the insider; withholding to cover taxes is common and does not necessarily signal a change in market view.