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Who owns SPRO?

Institutional ownership of Spero Therapeutics Inc. from Form 13F, Q2 2026

59 institutional managers reported holding Spero Therapeutics Inc. (SPRO) in Form 13F filings for Q2 2026, with 12,281,800 shares worth $27.2M. The largest reported holder was Pfizer Inc. Managers that filed both quarters added a net 382,209 shares (+3.2%). 21 opened new positions and 12 sold out.

Funds holding
59
Value held
$27.2M
New / sold out
21 / 12
Net shares, same filers
+3.2%

Holdings as of June 30, 2026, the end of Q2 2026. Managers have 45 days after a quarter ends to file Form 13F (by August 14, 2026 for Q2 2026), so positions may have changed since.

Largest holders of SPRO

FundValueShare of 13F holdingsSharesMove
Pfizer Inc$5.3M19.2%2,362,348Unchanged
Vanguard Capital Management LLC$4.5M16.6%2,036,226Added
Renaissance Technologies LLC$2.1M7.7%947,904Trimmed
Alphabet Inc.$2.0M7.2%889,979Unchanged
Susquehanna International Group, LLP$1.7M6.2%759,290Added
BlackRock, Inc.$1.3M4.8%594,404Added
Geode Capital Management, LLC$1.3M4.6%566,329Added
Raymond James Financial Inc$1.2M4.2%521,705New
Two Sigma Investments, LP$846K3.1%382,814Trimmed
Arrowstreet Capital, Limited Partnership$736K2.7%332,970New
Vanguard Fiduciary Trust Co$636K2.3%287,648Added
Gsa Capital Partners LLP$632K2.3%285,906Added
Dimensional Fund Advisors LP$608K2.2%274,820Added
Goldman Sachs Group Inc$568K2.1%256,985New
State Street Corp$475K1.7%214,751Unchanged
Jane Street Group, LLC$349K1.3%158,097Added
UBS Group AG$309K1.1%139,680Added
Bridgeway Capital Management, LLC$254K0.9%114,800Unchanged
Northern Trust Corp$239K0.9%108,274Trimmed
Point72 Asset Management, L.P.$231K0.8%104,377Added
Ionic Capital Management LLC$227K0.8%102,698Trimmed
Federation des caisses Desjardins du Quebec$202K0.7%91,900New
Shay Capital LLC$160K0.6%72,391Added
Invesco Ltd.$142K0.5%64,245Added
Simplex Trading, LLC$135K0.5%61,312Added

Share of 13F holdings is each fund's shares as a share of the 12,281,800 SPRO shares all 13F filers reported, not of shares outstanding.

Biggest buyers in Q2 2026

  1. Raymond James Financial Inc New+$1.2M
  2. Susquehanna International Group, LLP Added+$942K
  3. Arrowstreet Capital, Limited Partnership New+$736K
  4. Goldman Sachs Group Inc New+$568K
  5. Dimensional Fund Advisors LP Added+$542K
  6. Vanguard Capital Management LLC Added+$522K
  7. BlackRock, Inc. Added+$356K
  8. UBS Group AG Added+$302K
  9. Federation des caisses Desjardins du Quebec New+$202K
  10. Jane Street Group, LLC Added+$114K

Biggest sellers in Q2 2026

  1. Anson Funds Management LP Sold out-$2.0M
  2. Two Sigma Investments, LP Trimmed-$1.1M
  3. Citadel Advisors LLC Sold out-$881K
  4. Renaissance Technologies LLC Trimmed-$533K
  5. Squarepoint Ops LLC Sold out-$455K
  6. Marshall Wace, LLP Sold out-$368K
  7. Ionic Capital Management LLC Trimmed-$206K
  8. Quadrature Capital Ltd Sold out-$94K
  9. OMERS ADMINISTRATION Corp Sold out-$92K
  10. Schonfeld Strategic Advisors LLC Sold out-$48K

The change in shares since the quarter before, adjusted for stock splits and priced at the Q2 2026 value per share. Funds bought $6.5M and sold $5.9M; 17 added and 6 trimmed.

Questions about SPRO ownership

Who owns SPRO stock?
59 institutional investment managers reported SPRO positions in their Form 13F filings for Q2 2026, holding 12,281,800 shares worth $27.2M in total. Pfizer Inc reported the largest position.
Are funds buying or selling SPRO?
In Q2 2026, 21 managers opened new SPRO positions, 17 added, 6 trimmed and 12 sold out. Managers that filed in both quarters added a net 382,209 shares.
How current is this SPRO institutional ownership data?
It covers holdings as of the end of Q2 2026. Managers have 45 days after the quarter ends to file Form 13F (by August 14, 2026 for Q2 2026), so positions may have changed since.

From the SEC's Form 13F data sets for Q2 2026: every 13F holdings report, matched to SPRO by CUSIP. Options are left out. SPRO news and filings · SPRO insider trades · Top funds