Rajavelu Esther 4

What Happened Esther Rajavelu — listed as Chief Executive Officer, Chief Financial Officer and Chief Business Officer of Spero Therapeutics (SPRO) — sold 25,240 shares on May 4, 2026. The shares were sold at $2.51 each for a total proceeds of $63,352. This was a sale (not a purchase) and was executed to satisfy tax-withholding obligations tied to RSU vesting rather than a discretionary sell for investment reasons.

Key Details

• Transaction date and price: May 4, 2026 — 25,240 shares at $2.51 per share (total $63,352).
• Transaction type: Sale (code S); executed as a sell-to-cover for tax withholding (Footnote F1).
• Footnote: F1 states the shares were sold automatically to cover tax withholding for RSU vesting and do not represent a discretionary trade by the reporting person.
• Filed: Form 4 filed May 6, 2026 (two days after the transaction), which appears to be timely.
• Shares owned after transaction: Not reported in this Form 4.

Context Sell-to-cover transactions are routine when restricted stock units vest and taxes are due; they generally reflect tax mechanics rather than a change in the insider's view of the company. This filing documents a tax-withholding sale, not a deliberate market-timed disposition.