Mercury Systems Inc
MRCY- Exchange
- Nasdaq
- Industry
- Electronic Components & Accessories
- SEC CIK
- 0001049521
In the last 90 days, Mercury Systems Inc insiders filed 0 open-market purchases and 16 sales; 392 institutions reported holding it in 13F filings for Q2 2026, worth $8.01B in total; no superinvestor holds it.
Holders of 5% or more of MRCY
Holders whose latest Schedule 13D or 13G filing reports 5% or more of Mercury Systems Inc, largest stake first. The change is against the holder's previous filing.
| Holder | Latest form | Stake | Change | First filed | Latest filing | Filing |
|---|---|---|---|---|---|---|
| BlackRock, Inc. | 13G/A | 14.40%8.62M shares | +1.10 ppfrom 13.30% | Jul 17, 20252 filings | Jul 29, 2026 | SEC |
| JANA Partners Management, LP | 13D/A | 6.90%4.11M shares | −1.40 ppfrom 8.30% | Aug 15, 20253 filings | Mar 4, 2026 | SEC |
| State Street Corp | 13G | 6.40%3.87M shares | +1.40 ppfrom 5.00% | Feb 5, 20253 filings | May 12, 2026 | SEC |
| Vanguard Portfolio Management LLC | 13G | 5.13%3.09M shares | New | Jul 31, 20261 filing | Jul 31, 2026 | SEC |
Stakes are as of each holder's latest filing. Holders whose last filing was in the old format (before December 18, 2024) have no stake on record and are not listed, and after an acquisition or delisting holders usually stop filing.
13D and 13G filings
16 Schedule 13D and 13G filings on Mercury Systems Inc, newest first, including old-format filings without a stake.
| Filed (ET) | Filer | Form | Stake | Change | Event date | Filing |
|---|---|---|---|---|---|---|
| Jul 31, 202611:25 AM ET | Vanguard Portfolio Management LLC | 13G | 5.13%3.09M shares | New | Jun 30, 2026 | SEC |
| Jul 29, 20263:19 PM ET | BlackRock, Inc. | 13G/A | 14.40%8.62M shares | +1.10 ppfrom 13.30% | Jun 30, 2026 | SEC |
| May 12, 202611:34 AM ET | State Street Corp | 13G | 6.40%3.87M shares | +1.40 ppfrom 5.00% | Mar 31, 2026 | SEC |
| Mar 27, 202610:34 AM ET | Vanguard Group Inc | 13G/A | 0.00%0 shares | –Below 5% | Mar 13, 2026 | SEC |
| Mar 4, 20269:46 PM ET | JANA Partners Management, LP | 13D/A | 6.90%4.11M shares | −1.40 ppfrom 8.30% | Mar 3, 2026 | SEC |
| Nov 12, 20256:24 PM ET | William Blair Investment Management, LLC | 13G/A | 4.20%2.53M shares | −3.70 ppfrom 7.90%Below 5% | Sep 30, 2025 | SEC |
| Nov 10, 20256:30 PM ET | JANA Partners Management, LP | 13D/A | 8.30%4.97M shares | −1.70 ppfrom 10.00% | Nov 6, 2025 | SEC |
| Aug 15, 20259:30 PM ET | JANA Partners Management, LP | 13D/A | 10.00%5.96M shares | – | Aug 13, 2025 | SEC |
| Jul 30, 202511:21 AM ET | William Blair Investment Management, LLC | 13G/A | 7.90%4.70M shares | −1.10 ppfrom 9.00% | Jun 30, 2025 | SEC |
| Jul 17, 20258:12 PM ET | BlackRock, Inc. | 13G/A | 13.30%7.97M shares | – | Jun 30, 2025 | SEC |
| May 13, 202511:41 AM ET | State Street Corp | 13G | 5.00%2.99M shares | +0.10 ppfrom 4.90% | Mar 31, 2025 | SEC |
| May 9, 20253:18 PM ET | William Blair Investment Management, LLC | 13G/A | 9.00%5.37M shares | −1.80 ppfrom 10.80% | Mar 31, 2025 | SEC |
| Feb 12, 20255:52 PM ET | William Blair Investment Management, LLC | 13G/A | 10.80%6.43M shares | – | Dec 31, 2024 | SEC |
| Feb 5, 20257:01 AM ET | State Street Corp | 13G | 4.90%2.94M shares | NewBelow 5% | Dec 31, 2024 | SEC |
| Feb 11, 2021 | William Blair Investment Management, LLC | 13GOld format | – | New | – | SEC |
| Feb 10, 2021 | Vanguard Group Inc | 13G/AOld format | – | – | – | SEC |
Form 144: proposed insider sales
Notices from officers, directors and other affiliates planning to sell Mercury Systems Inc shares.
No Form 144 notices for Mercury Systems Inc are on file.