JANA Partners Management, LP: MERCURY SYS INC (MRCY): Quarterly 13F Position History
As of Q1 2026, JANA Partners Management, LP reported 4,107,424 shares of MERCURY SYS INC (MRCY), worth $299.5M and representing 18.6% of its 13F equity book. Quarter-over-quarter share count change: 852,057 (-17.2%) . The position first appeared in Q3 2023 and has been disclosed across 11 13F-HR filings in Pactolio's tracked window.
- 4,107,424Shares Held (Latest Filing)
- $299.5MReported Market Value (Latest Filing)
- 18.6%Portfolio Weight (% of 13F Equity Book)
- 852,057Quarter-over-Quarter Share Change
- -$62.6MQuarter-over-Quarter Value Change
- 6,941,565Peak Reported Shares (Historical)
Quarterly 13F-HR Disclosure History Source: SEC 13F-HR filings, 11 quarter s
| Quarter | Shares | QoQ Share Change | Share Change (%) | Market Value | Weight | Implied Price |
|---|---|---|---|---|---|---|
| Q1 2026 | 4,107,424 | 852,057 | -17.2% | $299.5M | 18.6% | $72.9 |
| Q4 2025 | 4,959,481 | 1,000,000 | -16.8% | $362.1M | 18.8% | $73.0 |
| Q3 2025 | 5,959,481 | 793,932 | -11.8% | $461.3M | 22.3% | $77.4 |
| Q2 2025 | 6,753,413 | 188,152 | -2.7% | $363.7M | 18.3% | $53.9 |
| Q1 2025 | 6,941,565 | 0 | — | $299.1M | 15.4% | $43.1 |
| Q4 2024 | 6,941,565 | 0 | — | $291.5M | 15.2% | $42.0 |
| Q3 2024 | 6,941,565 | +16,669 | +0.2% | $256.8M | 14.5% | $37.0 |
| Q2 2024 | 6,924,896 | 0 | — | $186.9M | 10.9% | $27.0 |
| Q1 2024 | 6,924,896 | +1,713,761 | +32.9% | $204.3M | 11.2% | $29.5 |
| Q4 2023 | 5,211,135 | +505,886 | +10.8% | $190.6M | 12.3% | $36.6 |
| Q3 2023 | 4,705,249 | — | — | $174.5M | 12.8% | $37.1 |
Methodology & FAQ
How This Position History Is Sourced
Each row is one SEC Form 13F-HR filing disclosing this position. Share count, market value, and reported quarter are taken verbatim from the filing; portfolio weight is recomputed against the same filing's total reported equity book. Implied price-per-share is market value divided by shares — a quarter-end mark, not the manager's cost basis. See the full methodology document for the normalization rules.
When did JANA Partners Management, LP first disclose a MRCY position in 13F-HR filings?
JANA Partners Management, LP first reported MERCURY SYS INC (MRCY) on its 13F-HR filing for the period ending 2023-09-30 (Q3 2023). The position has appeared on 11 reported quarters within Pactolio's tracked window.
What was JANA Partners Management, LP's most recent quarter-over-quarter share-count change in MRCY?
Between Q4 2025 and Q1 2026, JANA Partners Management, LP reduced its MRCY position by 852,057 shares (-17.2%), leaving 4,107,424 shares at a market value of $299.5M.
Does the implied price-per-share represent JANA Partners Management, LP's cost basis in MRCY?
No. The implied price-per-share column is the 13F-HR reported market value divided by reported share count on the filing date (end of quarter). It is a quarter-end mark, not a cost basis or transaction price. Use it as a sanity check on the value column, not as an indicator of the manager's entry or exit price.