Company · Ownership research

Spero Therapeutics, Inc. SPRO

CIK 0001701108 · CUSIP 84833T103

Insider tradingInitial holdingsInstitutional holders

Quarter-end disclosures, not live holdings.

Several CUSIPs are reported for this company; this page shows CUSIP 84833T103 (SPRO), not CUSIP 84833T953 (SPRO), CUSIP 84833T903 (SPRO), and does not merge CUSIPs.

This page lists the top 20 of 56 rows by value; the complete set is available through the API.

Some filings reported values in thousands; those figures were scaled ×1,000 to dollars.

Top 20 institutions

Weight means this stock's share of the manager's own portfolio.

By reported value

#	Manager	Value	Manager weight	Change vs prior	Source
01	GSK plc CIK 1131399 · View history	$21.41M 9,190,606 shares	2.68%	—	SEC filing ↗ Feb 12, 2026	▾
02	Pfizer Inc CIK 78003 · View history	$5.50M 2,362,348 shares	2.33%	0(0.00%)Unchanged	SEC filing ↗ Feb 12, 2026	▾
03	VANGUARD GROUP INC CIK 102909 · View history	$4.85M 2,083,462 shares	0.00%	+93.61K(+4.70%)Added	SEC filing ↗ Jan 29, 2026	▾
04	RENAISSANCE TECHNOLOGIES LLC CIK 1037389 · View history	$2.98M 1,279,522 shares	0.00%	-173.24K(-11.90%)Reduced	SEC filing ↗ Feb 12, 2026	▾
05	Alphabet Inc. CIK 1652044 · View history	$2.07M 889,979 shares	0.08%	0(0.00%)Unchanged	SEC filing ↗ Feb 13, 2026	▾
06	Anson Funds Management LP CIK 1491072 · View history	$1.46M 625,062 shares	0.19%	-978.51K(-61.00%)Reduced	SEC filing ↗ Feb 17, 2026	▾
07	GEODE CAPITAL MANAGEMENT, LLC CIK 1214717 · View history	$1.23M 529,195 shares	0.00%	+1.72K(+0.30%)Added	SEC filing ↗ Feb 9, 2026	▾
08	BlackRock, Inc. CIK 2012383 · View history	$1.01M 433,616 shares	0.00%	-1.15K(-0.30%)Reduced	SEC filing ↗ Feb 12, 2026	▾
09	CITADEL ADVISORS LLC CIK 1423053 · View history	$927.02K 397,864 shares	0.00%	+397.86KNew	SEC filing ↗ Feb 17, 2026	▾
10	TWO SIGMA INVESTMENTS, LP CIK 1179392 · View history	$868.09K 372,570 shares	0.00%	+323.17K(+654.20%)Added	SEC filing ↗ Feb 17, 2026	▾
11	SUSQUEHANNA INTERNATIONAL GROUP, LLP CIK 1446194 · View history	$684.32K 293,700 shares	0.00%	+293.70KNew	SEC filing ↗ Feb 17, 2026	▾
12	Informed Momentum Co LLC CIK 1510989 · View history	$508.14K 218,084 shares	0.06%	-64.36K(-22.80%)Reduced	SEC filing ↗ Feb 12, 2026	▾
13	TWO SIGMA ADVISERS, LP CIK 1478735 · View history	$504.68K 216,600 shares	0.00%	+216.60KNew	SEC filing ↗ Feb 17, 2026	▾
14	STATE STREET CORP CIK 93751 · View history	$489.65K 210,151 shares	0.00%	+19.20K(+10.10%)Added	SEC filing ↗ Feb 13, 2026	▾
15	Ionic Capital Management LLC CIK 1386462 · View history	$456.54K 195,939 shares	0.45%	-12.79K(-6.10%)Reduced	SEC filing ↗ Feb 17, 2026	▾
16	GSA CAPITAL PARTNERS LLP CIK 1362033 · View history	$417.00K 178,930 shares	0.04%	+72.04K(+67.40%)Added	SEC filing ↗ Feb 6, 2026	▾
17	INTREPID FAMILY OFFICE LLC CIK 1596197 · View history	$384.45K 165,000 shares	0.37%	+55.00K(+50.00%)Added	SEC filing ↗ Feb 17, 2026	▾
18	JANE STREET GROUP, LLC CIK 1595888 · View history	$368.94K 158,344 shares	0.00%	+115.36K(+268.30%)Added	SEC filing ↗ Feb 12, 2026	▾
19	SEI INVESTMENTS CO CIK 350894 · View history	$307.58K 132,010 shares	0.00%	+132.01KNew	SEC filing ↗ Feb 13, 2026	▾
20	OMERS ADMINISTRATION Corp CIK 1053321 · View history	$305.53K 131,127 shares	0.00%	+131.13KNew	SEC filing ↗ Feb 13, 2026	▾

Showing 20 / 56 institutions. The complete set is available through the API.

Coverage & totals by quarter

Reporting institutions

Cancelled or null records excluded

Disclosed shares

21,119,399

Not deduplicated across managers

Disclosed value

$49.21M

Not market cap or free float

Reporting institutions by quarter

Counts also change with data coverage and reporting entities; they do not measure net buying. Distinct managers with a live stock row in this CUSIP; totals may include overlapping filings and are not a share of the company.

Spero Therapeutics, Inc. · Q4 2025

Explore all 56 reporting institutions.

This page includes 20 of 56 reporting institutions. Log in to look up the full history beyond 3 years, use advanced screening & filtering, download CSV, and get the complete set through the Akkru API.

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Sources, coverage & how to read this data

Figures are as reported to the SEC and merged with later amendments where Akkru could match them. Preview limits apply to what is listed, not to the totals, which come from the complete reported data. Nothing is zero-filled: a missing quarter or month is shown as missing.