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Buy Day today: Neutral (52) Mixed market breadth · no major macro event
SPRO

Spero Therapeutics Inc

Healthcare · Biotechnology

0.9972$ -0.3% vs. previous close Closing price · As of: Nov 13, 2026

Ownership

Ownership Structure

Who owns Spero Therapeutics Inc (SPRO)? This page shows the largest institutions and funds, the ownership structure and the latest insider transactions. 80.9% of the shares are freely tradable; institutional investors hold 17.7%.

Institutional ownership ?Share of the stock held by institutional investors (funds, banks, insurers) according to regulatory filings. 17.7%
Insiders ?Share of the stock held by the executives, founders and major shareholders of the company itself. 22.7%
Float ?Share of stock freely tradable on the market — not locked up in the hands of founders, insiders, or major shareholders. 80.9%
Short % of float ?Shares sold short as a percentage of the freely tradable float — high values signal many bets on falling prices. 1.6%
Shares Outstanding ?Total number of shares issued. Price times share count gives market cap. 58Mio.

Largest Shareholders

Institutions

Institutions SPRO
Name Stake (%) Shares Change (%) Date
GSK PLC 15.78 9,190,606 +0.0 06/30/2026
Pfizer Inc 4.06 2,362,348 +0.0 06/30/2026
Vanguard Capital Management, LLC 3.50 2,036,226 +13.1 06/30/2026
Renaissance Technologies Corp 1.63 947,904 -20.3 06/30/2026
Alphabet Inc 1.53 889,979 +0.0 06/30/2026
Susquehanna International Group, LLP 1.30 759,290 +127.9 06/30/2026
BlackRock Inc 1.02 594,404 +37.2 06/30/2026
Geode Capital Management, LLC 0.97 566,329 +8.9 06/30/2026

Funds

Funds SPRO
Name Stake (%) Shares Change (%) Date
Vanguard MStar Total Stk Mkt Idx Invest 2.40 1,395,976 +0.0 09/30/2026
Mackenzie GQE US Small Cap F8 0.85 497,127 +0.0 08/31/2026

Largest reported positions according to regulatory filings; stake as a percentage of shares outstanding, change versus the previous filing. Source: fundamentals data.

Insider holdings

Insider holdings SPRO
Person Role Shares Value As of Type
Rajavelu Esther See Remarks 946,000 943,351 $ Nov 9, 2026 direct

Holdings as of each person's most recent SEC Form 4 filing — excluding options and RSUs, which are not shares yet. Holdings may have changed between two filings.

Insiders

Insider Transactions

Insider Transactions
Date Person Role Type Shares Price Value
Nov 9, 2026 Rajavelu Esther See Remarks Sell 40,851 1.04 42,485

Reportable transactions by officers and major shareholders from SEC Form 4 filings. "Other" includes things like stock grants and option exercises without a buy/sell character. View all insider transactions →

Data as of: November 13, 2026 · Source: fundamental data & SEC filings (annual and quarterly reports, 10-K/10-Q)

Note: pure fact-based analysis, not investment advice and not a solicitation to buy or sell. All figures without guarantee.

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