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Ken Griffin's Spero Therapeutics, Inc. (SPRO) position

Yes: as of Q1 2026, Ken Griffin holds 376K shares of SPRO worth an amount we cannot price (0.0% of the disclosed portfolio). Held since at least Q1 2021; that opening coverage snapshot is not counted as a purchase.
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Current value
an amount we cannot price
Shares held
376K
% of portfolio
0.0%
Quarter-end price
No quarter-end price available

Average buy price is hidden here because at least one covered purchase quarter has no usable local mean price.

SPRO price vs Griffin's position

Dates
$1$1.2$1.4$1.6← Earlier —8 purchases, 4 sells
Average closing price · filing quarter
Price range · filing quarter

Every quarterly change

Quarter Action Shares change Est. value change Δ Own Shares held Filing date
Q1 2026 Reduced −21K −5.4% 376K May 15, 2026
Q4 2025 New +398K 398K Feb 17, 2026
Q2 2025 Added +42K +69.3% 104K Aug 14, 2025
Q1 2025 Reduced −112K −64.5% 61K May 15, 2025
Q4 2024 Added +91K +112.3% 173K Feb 14, 2025
Q3 2024 Reduced −231K −73.9% 81K Nov 14, 2024
Q2 2024 New +312K 312K Aug 14, 2024
Q4 2023 New +32K 32K Feb 14, 2024
Q2 2023 New +15K 15K Aug 14, 2023
Q2 2022 Added +98K +903.5% 108K Aug 15, 2022
Q1 2022 New +11K 11K May 16, 2022
Q2 2021 Reduced −8K −41.2% 12K Aug 16, 2021
Q1 2021 First covered 20K May 21, 2021
Data through Q1 2026 · filed May 15, 2026
13 grouped rows from 13 quarters

More Griffin positions

Common questions

Does Ken Griffin own SPRO?

Yes. As of Q1 2026, Ken Griffin disclosed 376K shares of SPRO, worth an amount we cannot price. All figures come from SEC 13F filings for Q1 2026, the latest disclosed quarter.

When did Ken Griffin buy SPRO?

Ken Griffin held SPRO since at least Q1 2021, when this filing coverage begins; the opening snapshot is not a disclosed purchase. All figures come from SEC 13F filings for Q1 2026, the latest disclosed quarter.

Did Ken Griffin sell SPRO?

The quarter-by-quarter table above shows each sale and reduction Ken Griffin disclosed in SPRO. All figures come from SEC 13F filings for Q1 2026, the latest disclosed quarter.

How many shares of SPRO does Ken Griffin own?

Ken Griffin disclosed 376K shares of SPRO as of Q1 2026. All figures come from SEC 13F filings for Q1 2026, the latest disclosed quarter.

What price did Ken Griffin pay for SPRO?

Ken Griffin began building the SPRO position before our 13F history starts, so an exact average buy price cannot be estimated without understating it. All figures come from SEC 13F filings for Q1 2026, the latest disclosed quarter.

How are the estimated trade prices calculated?

13F filings disclose quarter-end holdings, not trade dates or execution prices. These estimates use each covered quarter's average market price; the add average excludes the opening position and quarters without price data. All figures come from SEC 13F filings for Q1 2026, the latest disclosed quarter.