Form 13-F position report

SPERO THERAPEUTICS INC

Reported by MORGAN STANLEY

Company profile Manager portfolio Source filing
SPRO CUSIP 84833T103 Manager CIK 0000895421
Latest reported change

Reported 4,552 shares, up 4,239 (1354.3%) from the prior quarter.

Reported value 1361.0%; share count 1354.3% vs. the prior quarter.

Added
% of reported 13F value < 0.01% This manager · Q1 2026
Shares 4,552 Quarter-end amount reported
Reported value $10,651 Fair value at quarter end
Consecutive quarters held 34 Through Q1 2026

Reported position value by quarter

Reported position value by quarter

Each bar is a Form 13-F quarter-end snapshot. It does not show trades made within the quarter.

Manager history

Quarterly position history

How this manager's reported quarter-end position changed over time.

20 quarters
Quarter Activity Shares Change % of reported 13F Reported value Filed
Q2 2026 Reduced 914 -3,638 (-79.9%) < 0.01% $2,020 2026-08-13
Q1 2026 Added 4,552 +4,239 (1354.3%) < 0.01% $10,651 2026-05-15
Q4 2025 Reduced 313 -43,065 (-99.3%) < 0.01% $729 2026-02-13
Q3 2025 Added 43,378 +34,157 (370.4%) < 0.01% $81,550 2025-11-14
Q2 2025 Added 9,221 +2,250 (32.3%) < 0.01% $26,741 2025-08-15
Q1 2025 Unchanged 6,971 0 (0.0%) < 0.01% $5,019 2025-05-15
Q4 2024 Unchanged 6,971 0 (0.0%) < 0.01% $7,180 2025-02-14
Q3 2024 Unchanged 6,971 0 (0.0%) < 0.01% $9,341 2024-11-14
Q2 2024 Reduced 6,971 -928 (-11.7%) < 0.01% $9,062 2024-08-14
Q1 2024 Reduced 7,899 -4,136 (-34.4%) < 0.01% $13,586 2024-05-15
Q4 2023 Added 12,035 +3,047 (33.9%) < 0.01% $17,691 2024-02-13
Q3 2023 Reduced 8,988 -542 (-5.7%) < 0.01% $10,875 2023-11-15
Q2 2023 Reduced 9,530 -5,700 (-37.4%) < 0.01% $13,819 2023-08-14
Q1 2023 Reduced 15,230 -1,847 (-10.8%) < 0.01% $22,084 2023-05-15
Q4 2022 Reduced 17,077 -2,177 (-11.3%) < 0.01% $29,543 2023-02-14
Q3 2022 Reduced 19,254 -174,355 (-90.1%) < 0.01% $38,000 2022-11-14
Q2 2022 Added 193,609 +120,613 (165.2%) < 0.01% $143,000 2022-08-15
Q1 2022 Added 72,996 +22,584 (44.8%) < 0.01% $635,000 2022-05-13
Q4 2021 Reduced 50,412 -6,089 (-10.8%) < 0.01% $807,000 2022-02-14
Q3 2021 Reduced 56,501 -13,271 (-19.0%) < 0.01% $1,041,000 2021-11-15
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Institutional context

Who else reported the position

63 managers reported SPERO THERAPEUTICS INC for Q1 2026.

Manager Activity Shares Change % of reported 13F Reported value Tenure
GSK plc Unchanged 9,190,606 0 3.59% $21,506,018 2 qtrs
PFIZER INC Unchanged 2,362,348 0 2.31% $5,504,271 6 qtrs
VANGUARD CAPITAL MANAGEMENT LLC New 1,799,880 +1,799,880 < 0.01% $4,211,719 1 qtr
RENAISSANCE TECHNOLOGIES LLC Reduced 1,189,235 -90,287 < 0.01% $2,782,810 17 qtrs
Alphabet Inc Unchanged 889,979 0 0.05% $2,082,551 34 qtrs
TWO SIGMA INVESTMENTS LP Added 885,631 +513,061 < 0.01% $2,072,377 3 qtrs
GEODE CAPITAL MANAGEMENT LLC Reduced 519,922 -9,273 < 0.01% $1,217,170 33 qtrs
BlackRock Inc Reduced 433,202 -414 < 0.01% $1,013,693 7 qtrs
Anson Funds Management LP Reduced 421,956 -203,106 0.09% $987,377 15 qtrs
CITADEL ADVISORS LLC Reduced 376,458 -21,406 < 0.01% $880,912 12 qtrs
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Filing details and methodology As reported
Report period
March 31, 2026
Filed
May 15, 2026
Filing type
13F-HR
Position type
COM

Voting authority reported

Sole
4,252
Shared
0
None
300

“None” means the manager reported no voting authority for those shares on non-routine matters. It does not disclose why and is not evidence of securities lending.

Form 13-F is a delayed quarter-end snapshot of disclosed long Section 13(f) securities. It can be filed up to 45 days after quarter end, excludes short positions and most non-U.S. securities, and does not reveal intra-quarter trading. For options, reported shares and value describe the underlying-share exposure; strike, expiry, premium, and written positions are not disclosed.