InsiderSource
SPRO

Spero Therapeutics, Inc.

SEC CIK 1701108
$2.85 +24.5% · 90 days
90-day buys
$0
0 open-market
90-day sells
$63.4K
1 open-market
Net insider flow
−$63.4K
Net selling
Filings shown
39
Most recent
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At a glance

Over the last 90 days, insiders at SPRO have sold a net $63.4K of stock (0 open-market buys vs 1 sell).

Largest recent trade: Rajavelu Esther sold $119.9K of SPRO, trimming their stake 5%.

Most active filer: Rajavelu Esther, with 11 transactions among the recent filings shown.

Insider transaction history

Form 4 filings for SPRO, newest first
View on SEC EDGAR ↗
SPRO
Spero Therapeutics, Inc.
Sell Rajavelu Esther · See Remarks · Open-market sale · filed May 6, 2026 ΔOwn −2.5%

Rajavelu Esther sold $63.4K of SPRO, trimming their stake 2%.

−$63.4K
25,240 sh @ $3
SPRO
Spero Therapeutics, Inc.
Sell Rajavelu Esther · See Remarks · Open-market sale · filed Feb 9, 2026 ΔOwn −3.4%

Rajavelu Esther sold $87.6K of SPRO, trimming their stake 3%.

−$87.6K
37,101 sh @ $2
SPRO
Spero Therapeutics, Inc.
Sell Rajavelu Esther · See Remarks · Open-market sale · filed Feb 9, 2026 ΔOwn −4.8%

Rajavelu Esther sold $119.9K of SPRO, trimming their stake 5%.

−$119.9K
50,816 sh @ $2
SPRO
Spero Therapeutics, Inc.
Sell Keutzer Timothy · Chief Operating Officer · Open-market sale · filed Feb 9, 2026 ΔOwn −2.5%

Keutzer Timothy sold $44K of SPRO, trimming their stake 2%.

−$44K
18,652 sh @ $2
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SPRO
Spero Therapeutics, Inc.
Sell Keutzer Timothy · Chief Operating Officer · Open-market sale · filed Feb 5, 2026 ΔOwn −3.1%

Keutzer Timothy sold $51.8K of SPRO, trimming their stake 3%.

−$51.8K
24,224 sh @ $2
SPRO
Spero Therapeutics, Inc.
Sell Keutzer Timothy · Chief Operating Officer · Open-market sale · filed Feb 5, 2026 ΔOwn −2.3%

Keutzer Timothy sold $41.6K of SPRO, trimming their stake 2%.

−$41.6K
18,891 sh @ $2
SPRO
Spero Therapeutics, Inc.
Sell Rajavelu Esther · See Remarks · Open-market sale · filed Feb 4, 2026 ΔOwn −1.6%

Rajavelu Esther sold $40.6K of SPRO, trimming their stake 2%.

−$40.6K
18,442 sh @ $2
SPRO
Spero Therapeutics, Inc.
Sell Rajavelu Esther · See Remarks · Open-market sale · filed Nov 12, 2025 ΔOwn −4.4%

Rajavelu Esther sold $95.4K of SPRO, trimming their stake 4%.

−$95.4K
40,270 sh @ $2
SPRO
Spero Therapeutics, Inc.
Sell Mahadevia Ankit · Director · Open-market sale · filed Sep 3, 2025 ΔOwn −0.9%

Mahadevia Ankit sold $12.9K of SPRO, trimming their stake 1%.

−$12.9K
6,572 sh @ $2
SPRO
Spero Therapeutics, Inc.
Sell Keutzer Timothy · Chief Operating Officer · Open-market sale · filed Feb 5, 2025 ΔOwn −3.5%

Keutzer Timothy sold $21.6K of SPRO, trimming their stake 3%.

−$21.6K
27,643 sh @ $1
SPRO
Spero Therapeutics, Inc.
Sell Keutzer Timothy · Chief Operating Officer · Open-market sale · filed Feb 5, 2025 ΔOwn −3.3%

Keutzer Timothy sold $19.4K of SPRO, trimming their stake 3%.

−$19.4K
24,920 sh @ $1
SPRO
Spero Therapeutics, Inc.
Sell Rajavelu Esther · CFO & CBO · Open-market sale · filed Feb 5, 2025 ΔOwn −2.8%

Rajavelu Esther sold $16.1K of SPRO, trimming their stake 3%.

−$16.1K
20,689 sh @ $1
SPRO
Spero Therapeutics, Inc.
Sell Shukla Sath · CEO & President · Open-market sale · filed Feb 5, 2025 ΔOwn −0.3%

Shukla Sath sold $4.8K of SPRO.

−$4.8K
6,139 sh @ $1
SPRO
Spero Therapeutics, Inc.
Sell Shukla Sath · CEO & President · Open-market sale · filed Feb 5, 2025 ΔOwn −2.3%

Shukla Sath sold $33.4K of SPRO, trimming their stake 2%.

−$33.4K
42,786 sh @ $1
SPRO
Spero Therapeutics, Inc.
Sell Shukla Sath · CEO & President · Open-market sale · filed Feb 5, 2025 ΔOwn −5.8%

Shukla Sath sold $83K of SPRO, trimming their stake 6%.

−$83K
106,408 sh @ $1
SPRO
Spero Therapeutics, Inc.
Sell Mahadevia Ankit · Director · Open-market sale · filed Feb 5, 2025 ΔOwn −1.8%

Mahadevia Ankit sold $10.9K of SPRO, trimming their stake 2%.

−$10.9K
13,959 sh @ $1
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About SPRO insider activity

This page tracks every recent Form 4 filed for Spero Therapeutics, Inc. with the U.S. Securities and Exchange Commission. Form 4 is the disclosure that company insiders — officers, directors, and holders of more than 10% of the stock — must file within two business days of buying or selling shares.

The summary above nets open-market purchases against open-market sales over the trailing 90 days. Open-market trades (codes P and S) tend to carry the most signal because they reflect a deliberate choice to put money in or take it out, as opposed to routine grants, option exercises, or tax-withholding events. Use the badges on each row to tell them apart, and always confirm details against the original filing before drawing conclusions.

Frequently asked questions

How often is SPRO insider data updated?

Continuously. We read from SEC EDGAR, so new Form 4 filings for Spero Therapeutics, Inc. usually appear here within minutes of being accepted by the SEC.

What does "net insider flow" mean?

It is the total dollar value of open-market insider purchases minus open-market sales over the last 90 days. A positive number (green) means insiders bought more than they sold; a negative number (red) means the reverse.

Why do some rows show grants or option exercises instead of buys?

Insiders receive stock through compensation as well as buying it outright. Form 4 captures all of these. We label each transaction by its SEC code so you can focus on open-market activity if you prefer.

Is this investment advice?

No. InsiderSource presents public filing data for informational purposes only. Insider activity is one of many factors to consider and is never a recommendation to buy or sell.