Spero Therapeutics Ownership & Insider Activity

Spero Therapeutics (SPRO) institutional and insider ownership, recent insider transactions and ownership breakdown.

Insiders own 11.0% of shares outstanding. Institutional investors hold 9.5%.

Shares Outstanding

58.235M

Shares Float

48.308M

Insider Shares Owned

6.404M

Insider % Owned

11.0%

Institutional Shares Held

5.557M

Institutional % Held

9.5%

Ownership Breakdown

Net Insider Activity by Month

Spero Therapeutics Insider Transactions (Last 6 Months)

Date	Insider	Title	Type	Shares	Price	Value
May 4, 2026	Esther Rajavelu	SEE REMARKS	SELL	25.240K	$2.51	$63K