Timothy Keutzer, Chief Operating Officer of Spero Therapeutics (NASDAQ: SPRO), completed a stock sale on February 6, 2026, disposing of 18,652 shares at $2.36 per share. The transaction generated proceeds of $44,018 and, according to a Form 4 filed with the Securities and Exchange Commission, the sale was executed to meet tax withholding obligations connected to the vesting of Restricted Stock Units (RSUs).
After the sale, Keutzer's direct ownership in Spero stands at 742,506 shares. The Form 4 filing specifies the tax-related rationale for the disposition rather than an open-market investment decision, noting the sale's administrative purpose tied to equity compensation.
In separate corporate updates, Spero announced that Dr. Ankit Mahadevia has resigned from its Board of Directors and associated roles, citing other professional commitments. The company stated it intends to engage Dr. Mahadevia under a consulting agreement to continue providing support to Spero's management team.
Also disclosed was the conclusion of an SEC inquiry into the company. Spero reported that the U.S. Securities and Exchange Commission indicated no enforcement action is currently planned against the company as a result of that inquiry.
On the regulatory and commercial front, Spero said that GSK has resubmitted a New Drug Application to the U.S. Food and Drug Administration for tebipenem HBr, Spero's oral antibiotic candidate intended to treat complicated urinary tract infections, including pyelonephritis. The NDA resubmission is tied to a contractually defined milestone payment of $25 million to Spero, which the company expects to receive in the first quarter of 2026.
Taken together, the disclosures cover an insider tax-driven share sale, a board-level personnel change with a planned consulting arrangement, closure of an SEC inquiry without immediate enforcement, and a material near-term milestone payment contingent on an NDA resubmission. Each item represents a discrete operational, governance or regulatory development relevant to Spero's corporate trajectory and near-term cash flow expectations.