Spero Exec Buys 249k Shares on RSU Grant, Then Sells to Cover Taxes – A Bullish Signal Amid Volatility

Insider Activity Highlights Strategic Confidence Amid Volatility

The latest Form 4 filing from Rajavelu Esther on February 2, 2026 shows a significant purchase of 249,000 shares of Spero Therapeutics’ common stock, executed at the then‑trading price of $2.29. The transaction is tied to a restricted‑stock‑unit (RSU) grant under the company’s 2017 Stock Incentive Plan, with vesting beginning on February 2, 2027. While the buy itself is a standard compensation event, the sheer volume of shares—raising her post‑transaction holdings to 1,118,450—signals a long‑term commitment that investors may view as a vote of confidence in the company’s pipeline and management team.

Tax‑Covering Sale Balances Liquidity Needs

Shortly after the RSU grant, Esther sold 18,442 shares at $2.20 to cover the tax obligations associated with the vesting of those units. This sell‑to‑cover transaction is routine for executives receiving RSUs; it does not reflect a discretionary divestment but rather a cash‑flow necessity. The net effect is that Esther’s overall stake remains robust, underscoring her willingness to remain invested as the company pursues its antibacterial drug development strategy.

Contextualizing with Company‑Wide Insider Moves

Spero’s insider landscape has not been idle. In late August 2025, COO Timothy Keutzer and fellow director Ankit Mahadevia each sold portions of their holdings (1,695 and 6,572 shares, respectively) at $1.97. Those sales occurred after the company’s 2025 earnings release, which saw a modest decline in share price. While such trades often trigger scrutiny, they are not uncommon in biotech firms where insiders may liquidate shares for diversification or personal liquidity. Compared to Esther’s RSU‑linked activity, the August sales appear more routine and less indicative of a change in confidence.

Implications for Investors and the Company’s Future

From an investment standpoint, Esther’s sizable RSU purchase coupled with a tax‑covering sale suggests she remains optimistic about Spero’s trajectory, especially as the company advances its novel MDR bacterial therapies. Her long‑term stake aligns with the company’s strategic milestones, such as clinical trial progress and potential regulatory approvals. The fact that the share price remains below the 200‑day moving average and the company’s P/E is negative highlights the valuation challenges and the need for future earnings turnaround. However, the recent 165% yearly gain and a market cap of $123 million demonstrate that the market is still pricing in significant upside potential.

What This Means for the Bottom Line

For shareholders, the insider activity paints a mixed picture. The RSU purchase is a bullish signal, yet the company’s current valuation metrics suggest caution. Investors should monitor upcoming clinical data releases and any progress toward commercialization, which could unlock the stock’s intrinsic value. Meanwhile, the ongoing insider sales indicate that executives are managing personal liquidity without fundamentally altering their ownership positions. Overall, the insider actions point to a company in transition—striving for breakthroughs while navigating the typical volatility of early‑stage biotechnology.