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 45 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	Pfizer Inc CIK 78003 · View history	$6.85M 2,362,348 shares	1.19%	0(0.00%)Unchanged	SEC filing ↗ Aug 11, 2025	▾
02	VANGUARD GROUP INC CIK 102909 · View history	$5.66M 1,950,381 shares	0.00%	+186.76K(+10.60%)Added	SEC filing ↗ Aug 11, 2025	▾
03	Anson Funds Management LP CIK 1491072 · View history	$4.68M 1,615,469 shares	0.86%	-2.18M(-57.50%)Reduced	SEC filing ↗ Aug 14, 2025	▾
04	Alphabet Inc. CIK 1652044 · View history	$2.58M 889,979 shares	0.12%	0(0.00%)Unchanged	SEC filing ↗ Aug 1, 2025	▾
05	RENAISSANCE TECHNOLOGIES LLC CIK 1037389 · View history	$2.41M 832,165 shares	0.00%	-138.74K(-14.30%)Reduced	SEC filing ↗ Aug 13, 2025	▾
06	Schonfeld Strategic Advisors LLC CIK 1665241 · View history	$1.48M 510,834 shares	0.01%	+510.83KNew	SEC filing ↗ Aug 14, 2025	▾
07	GEODE CAPITAL MANAGEMENT, LLC CIK 1214717 · View history	$1.48M 510,699 shares	0.00%	-14.17K(-2.70%)Reduced	SEC filing ↗ Aug 8, 2025	▾
08	BlackRock, Inc. CIK 2012383 · View history	$1.26M 434,768 shares	0.00%	-47.31K(-9.80%)Reduced	SEC filing ↗ Aug 12, 2025	▾
09	MONIMUS CAPITAL MANAGEMENT, LP CIK 1848831 · View history	$901.63K 310,908 shares	0.72%	0(0.00%)Unchanged	SEC filing ↗ Aug 15, 2025	▾
10	Informed Momentum Co LLC CIK 1510989 · View history	$693.51K 239,140 shares	0.11%	+239.14KNew	SEC filing ↗ Aug 12, 2025	▾
11	Stonepine Capital Management, LLC CIK 1440771 · View history	$454.98K 156,888 shares	0.45%	+156.89KNew	SEC filing ↗ Aug 13, 2025	▾
12	STATE STREET CORP CIK 93751 · View history	$445.01K 153,451 shares	0.00%	+4.54K(+3.00%)Added	SEC filing ↗ Aug 14, 2025	▾
13	Ionic Capital Management LLC CIK 1386462 · View history	$435.00K 150,000 shares	0.49%	+150.00KNew	SEC filing ↗ Aug 14, 2025	▾
14	ADAR1 Capital Management, LLC CIK 1940272 · View history	$417.36K 143,917 shares	0.07%	-657.36K(-82.00%)Reduced	SEC filing ↗ Aug 14, 2025	▾
15	BRIDGEWAY CAPITAL MANAGEMENT, LLC CIK 1107261 · View history	$332.92K 114,800 shares	0.01%	-40.00K(-25.80%)Reduced	SEC filing ↗ Aug 14, 2025	▾
16	ACADIAN ASSET MANAGEMENT LLC CIK 916542 · View history	$327.00K 112,889 shares	0.00%	-758.32K(-87.00%)Reduced	SEC filing ↗ Aug 7, 2025	▾
17	CITADEL ADVISORS LLC CIK 1423053 · View history	$300.98K 103,786 shares	0.00%	+42.47K(+69.30%)Added	SEC filing ↗ Aug 14, 2025	▾
18	NORTHERN TRUST CORP CIK 73124 · View history	$292.41K 100,831 shares	0.00%	-93(-0.10%)Reduced	SEC filing ↗ Aug 13, 2025	▾
19	SUSQUEHANNA INTERNATIONAL GROUP, LLP CIK 1446194 · View history	$202.46K 69,814 shares	0.00%	+69.81KNew	SEC filing ↗ Aug 14, 2025	▾
20	XTX Topco Ltd CIK 1828301 · View history	$100.20K 34,551 shares	0.00%	+34.55KNew	SEC filing ↗ Aug 12, 2025	▾

Showing 20 / 45 institutions. The complete set is available through the API.

Coverage & totals by quarter

Reporting institutions

Cancelled or null records excluded

Disclosed shares

11,078,704

Not deduplicated across managers

Disclosed value

$32.13M

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. · Q2 2025

Explore all 45 reporting institutions.

This page includes 20 of 45 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.

Download CSV
Earlier quarters
Advanced screening & filtering
API & AI access

Already have an account?

＋ New accounts get free API credits to explore data beyond ownership filings.

For AI agents & developers

The initial HTML of this page carries its exact data as script#research-data (JSON): values, units, scope, preview limits and SEC sources. Read it directly, no script or API key needed; script#research-access says what needs an account. This page lists 20 of 45 reporting institutions; totals use the complete disclosed data.

Without an account: the last 3 years, with the row caps stated on the page. A free account opens all history on file on these pages and the CSV of what a page shows. Rows beyond the caps and bulk retrieval go through the authenticated API / MCP / CLI.

MCP  https://api.akkrudata.ai/mcp

akkru_institutional_holdings
{"action":"holders","cusip":"84833T103","quarter":"2025Q2","type":"positions","page_size":100}

Connect to MCP with OAuth and follow the returned pagination. Credits and usage limits depend on the account.

MCP endpoint: https://api.akkrudata.ai/mcp
API / MCP / CLI documentation: /documents
llms.txt: /llms.txt

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.