Spero Therapeutics Ownership | Who Owns Spero Therapeutics?

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Spero Therapeutics Ownership Summary

Spero Therapeutics is owned by 5.64% institutional investors, 24.36% insiders, and 70.01% retail investors. Pfizer is the largest institutional shareholder, holding 4.22% of SPRO shares. Vanguard US Total Market Shares ETF is the top mutual fund, with 2.09% of its assets in Spero Therapeutics shares.

SPRO Ownership Benchmark

Type	Name	% Inst	% Insiders	% Retail
Stock	Spero Therapeutics	5.64%	24.36%	70.01%
Sector	Healthcare Stocks	42.54%	10.83%	46.63%
Industry	Biotech Stocks	45.22%	10.75%	44.04%

Institutional Shareholders

Top Institutional Shareholders by Total Shares

Holder	Shares	% Holding	Value
Pfizer	2.36M	4.22%	$4.44M
Vanguard group	1.99M	3.55%	$3.74M
Anson funds management lp	1.60M	2.86%	$3.01M
Renaissance	1.45M	2.59%	$2.73M
Alphabet	889.98K	1.59%	$1.67M
Geode capital management	527.48K	0.94%	$991.89K
Blackrock	483.40K	0.90%	$628.42K
Blackrock funding, inc. /de	434.77K	0.78%	$817.36K
Awm investment company	333.40K	0.62%	$433.42K
Eam investors	282.44K	0.50%	$531.00K

Top Institutional Shareholders by % of Total Assets

Holder	Shares	% Assets	Value
Pfizer	2.36M	1.02%	$4.44M
Anson funds management lp	1.60M	0.27%	$3.01M
Intrepid family office	110.00K	0.17%	$206.80K
Alphabet	889.98K	0.07%	$1.67M
Eam investors	282.44K	0.06%	$531.00K
Awm investment company	333.40K	0.06%	$433.42K
Rangeley capital	30.00K	0.05%	$56.40K
Ionic capital management	208.72K	0.04%	$392.40K
Adar1 capital management	115.54K	0.02%	$217.21K
Gsa capital partners llp	106.89K	0.02%	$201.00K

Top Buyers

Holder	Shares	% Assets	Change
Renaissance	1.45M	0.00%	620.60K
Arrowstreet capital, limited partnership	150.52K	0.00%	150.52K
Intrepid family office	110.00K	0.17%	110.00K
Gsa capital partners llp	106.89K	0.02%	106.89K
Shay capital	63.67K	0.01%	63.67K

Top Sellers

Holder	Shares	% Assets	Change
Murchinson	-	-	-873.91K
Schonfeld strategic advisors	-	-	-510.83K
Novo	-	-	-468.90K
Monimus capital management, lp	-	-	-310.91K
Atlas venture life science advisors	-	-	-305.25K

New Positions

Holder	Shares	% Assets	Change	Value
Arrowstreet capital, limited partnership	150.52K	0.00%	150.52K	$282.97K
Intrepid family office	110.00K	0.17%	110.00K	$206.80K
Gsa capital partners llp	106.89K	0.02%	106.89K	$201.00K
Shay capital	63.67K	0.01%	63.67K	$119.69K
Two sigma investments, lp	49.40K	0.00%	49.40K	$92.87K

Sold Out

Holder	Change
Qube research	-1.00
Federation des caisses desjardins du quebec	-30.00
Northwestern mutual wealth management	-50.00
Pfs partners	-50.00
Corecap advisors	-50.00

Institutional Ownership Trends

Date	Holdings	Change %	Shares	Change %	Ownership	Change %	Increased Position	Change %	Decreased Position	Change %
Sep 30, 2025	11	-74.42%	3,157,628	-71.20%	5	1.47%	3	-86.96%	1	-88.89%
Jun 30, 2025	45	9.76%	11,078,414	-26.67%	19	2.66%	24	118.18%	9	-10.00%
Mar 31, 2025	4	-92.31%	2,111,095	-86.54%	3	0.47%	-	-100.00%	-	-100.00%
Dec 31, 2024	52	10.64%	15,679,985	27.34%	28	5.60%	26	160.00%	9	-25.00%
Sep 30, 2024	47	-4.08%	12,313,754	-11.17%	22	3.39%	10	-41.18%	12	50.00%

Top Mutual Funds Shareholders

Holder	Shares	% Holding	Change
Vanguard US Total Market Shares ETF	1.17M	2.09%	-
Vanguard Total Stock Mkt Idx Inv	1.14M	2.03%	-25.17K
Vanguard Institutional Extnd Mkt Idx Tr	516.11K	0.92%	-235.18K
IMC US Ultra Micro Cap	255.33K	0.45%	-
Fidelity Extended Market Index	236.38K	0.42%	-1.11K
Pleiades Small Cap Equity A	127.66K	0.23%	127.66K
Fidelity Total Market Index	108.76K	0.19%	-231.00
Extended Equity Market Fund K	107.09K	0.19%	47.16K
iShares Micro-Cap ETF	87.05K	0.16%	-
Mackenzie US Small Cap A	65.79K	0.12%	-

Recent Insider Transactions

Date	Name	Role	Activity	Value
Nov 07, 2025	Rajavelu Esther	See Remarks	Sell	$95.44K
Aug 28, 2025	Mahadevia Ankit	-	Sell	$12.95K
Aug 28, 2025	Keutzer Timothy	Chief Operating Officer	Sell	$3.34K
Feb 05, 2025	Keutzer Timothy	Chief Operating Officer	Sell	$3.10K
Feb 05, 2025	Keutzer Timothy	Chief Operating Officer	Sell	$21.56K

Insider Transactions Trends

Date	Buy	Sell
2025 Q1	-	9
2024 Q4	-	2
2024 Q3	-	5
2024 Q2	-	-
2024 Q1	-	6

SPRO Ownership FAQ

Who Owns Spero Therapeutics?

Spero Therapeutics shareholders are primarily institutional investors at 5.64%, followed by 24.36% insiders and 70.00% retail investors. The average institutional ownership in Spero Therapeutics's industry, Biotech Stocks , is 45.22%, which Spero Therapeutics falls below.

Who owns the most shares of Spero Therapeutics?

Spero Therapeutics’s largest shareholders are Pfizer (2.36M shares, 4.22%), Vanguard group (1.99M shares, 3.55%), and Anson funds management lp (1.6M shares, 2.86%). Together, they hold 10.63% of Spero Therapeutics’s total shares outstanding.

Does Blackrock own Spero Therapeutics?

Yes, BlackRock owns 0.90% of Spero Therapeutics, totaling 483.4K shares as of Jun 2024. This represents 0% of BlackRock's total assets, with a market value of 628.42K$. In the last quarter, BlackRock increased its holdings by 6.51K shares, a 1.36% change.

Who is Spero Therapeutics’s biggest shareholder by percentage of total assets invested?

Pfizer is Spero Therapeutics’s biggest shareholder by percentage of total assets invested, with 1.02% of its assets in 2.36M Spero Therapeutics shares, valued at 4.44M$.

Who is the top mutual fund holder of Spero Therapeutics shares?

Vanguard US Total Market Shares ETF is the top mutual fund holder of Spero Therapeutics shares, with 2.09% of its total shares outstanding invested in 1.17M Spero Therapeutics shares.

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