JANA Partners Management, LPtracked
Open in PORT →Compare →Tear sheet →← all managersCIK 1998597
Reported long US book (13F) · Δ vs 2025-Q4 · methodology
Implied return what this book implies methodology →
As filed = each book applied at quarter-end (what it did) · As copyable = applied at the 45-day filing deadline (what a follower could have earned).
Computing…
Exposures · what it owns, by sector & size (2026-Q1)
By sector
By market cap
By region
By industry group GICS — finer than sector
| Industry group | Weight | Names |
|---|---|---|
| Semiconductors & Semiconductor Equipment | 18.65% | 1 |
| Health Care Equipment & Supplies | 15.87% | 1 |
| Unclassified | 15.75% | 2 |
| Commercial Services & Supplies | 15.41% | 1 |
| Food Products | 13.18% | 1 |
| Insurance | 8.98% | 1 |
| Software | 7.61% | 2 |
| Entertainment | 4.55% | 1 |
Top holdings
| # | Ticker | Name | Sector | Weight |
|---|---|---|---|---|
| 1 | MRCY | MERCURY SYSTEMS INC | Information Technology | 18.65% |
| 2 | COO | COOPER COMPANIES, INC. | Health Care | 15.87% |
| 3 | FISV | FISERV INC | Financials | 15.41% |
| 4 | SPY | STATE STR SPDR S&P 500 ETF T | Unclassified | 13.92% |
| 5 | LW | Lamb Weston Holdings, Inc. | Consumer Staples | 13.18% |
| 6 | MKL | MARKEL GROUP INC. | Financials | 8.98% |
| 7 | ALKT | ALKAMI TECHNOLOGY, INC. | Information Technology | 5.30% |
| 8 | FUN | Six Flags Entertainment Corporation/NEW | Communication Services | 4.55% |
| 9 | RPD | Rapid7, Inc. | Information Technology | 2.31% |
| 10 | EHAB | ENHABIT INC | Unclassified | 1.83% |
8/10 classified; unclassified names are still shown.
Sector allocation over time · how the sector mix & top names shifted each quarter
Sector allocation over 11 reported quarters, 2023-Q3 to 2026-Q1, 21 bands (top holdings within each sector). Latest quarter 2026-Q1: MRCY 18.6%, COO 15.9%, FISV 15.4%, SPY 13.9%, LW 13.2%. Use the arrow keys to read a quarter.
Sector is classified on each name's CURRENT fundamentals, not point-in-time — apparent sector drift can reflect the market re-rating a holding, not a manager trade. 13F is a lagged quarterly snapshot of long positions in US-listed securities only — foreign companies held via a US listing or ADR ARE included, but shares listed only on non-US exchanges (plus shorts, options and cash) are not. Latest quarter: 84.2% of the book is classified (unclassified names are still shown).
Style box · size × value-growth placement (2026-Q1), classified on today's fundamentals (not point-in-time) — load into PORT to overlay your own book
Classified: 61.1% of book weight (6/10 names) · unclassified 38.9%.
Contribution holdings-based, any period
Attribution lands once this book has priced history across the window. Try a longer period.
Holdings· 10 positions (2026-Q1) · largest first · Δ vs 2025-Q4
| # | Security | Shares | Value | Weight | Δ QoQ |
|---|---|---|---|---|---|
| 1 | MRCYMERCURY SYS INC | 4,107,424 | $299M | 18.6% | TRIM −17% |
| 2 | COOCOOPER COS INC | 3,565,158 | $255M | 15.9% | HOLD |
| 3 | FISVFISERV INC | 4,435,605 | $248M | 15.4% | ADD 98% |
| 4 | SPYSTATE STR SPDR S&P 500 ETF T | 343,665 | $223M | 13.9% | TRIM −12% |
| 5 | LWLAMB WESTON HLDGS INC | 5,008,635 | $212M | 13.2% | HOLD |
| 6 | MKLMARKEL GROUP INC | 75,307 | $144M | 9.0% | TRIM −7% |
| 7 | ALKTALKAMI TECHNOLOGY INC | 5,431,388 | $85M | 5.3% | ADD 11% |
| 8 | FUNSIX FLAGS ENTERTAINMENT CORP | 4,116,099 | $73M | 4.5% | HOLD |
| 9 | RPDRAPID7 INC | 6,743,653 | $37M | 2.3% | HOLD |
| 10 | EHABENHABIT INC | 2,090,412 | $29M | 1.8% | HOLD |
Position trends· top 10 holdings · shares held over 6 quarters
| Security | 2024-Q4 | 2025-Q1 | 2025-Q2 | 2025-Q3 | 2025-Q4 | 2026-Q1 | Latest value |
|---|---|---|---|---|---|---|---|
| MRCYMERCURY SYS INC | 6.9M | 6.9M | 6.8M | 6.0M | 5.0M | 4.1M | $299M |
| COOCOOPER COS INC | — | — | — | 2.4M | 3.5M | 3.6M | $255M |
| FISVFISERV INC | — | — | — | — | 2.2M | 4.4M | $248M |
| SPYSTATE STR SPDR S&P 500 ETF T | 429K | 540K | 513K | 387K | 391K | 344K | $223M |
| LWLAMB WESTON HLDGS INC | 7.1M | 8.0M | 7.2M | 5.0M | 5.0M | 5.0M | $212M |
| MKLMARKEL GROUP INC | 109K | 156K | 151K | 147K | 81K | 75K | $144M |
| ALKTALKAMI TECHNOLOGY INC | — | — | — | 1.9M | 4.9M | 5.4M | $85M |
| FUNSIX FLAGS ENTERTAINMENT CORP | — | — | — | 4.0M | 4.1M | 4.1M | $73M |
| RPDRAPID7 INC | 3.7M | 4.1M | 5.7M | 6.5M | 6.7M | 6.7M | $37M |
| EHABENHABIT INC | 2.1M | 2.1M | 2.1M | 2.1M | 2.1M | 2.1M | $29M |
Green = added, red = trimmed, grey = held; a dash is a quarter with no 13F on file — a gap, not an exit.
Related· where to look next
Where this firm's principals came from, and what its alumni went on to found.
joins filed 13F data only — no style, strategy or performance similarity is claimed · 13F 2026-Q1
Also hold MRCY — other Section 13(f) filers reporting a long position in this book's largest tickered holding for 2026-Q1. Lagged quarterly filings (up to 45 days after quarter-end); “% of shares out” is omitted where the reported share count can't carry it. Institutional 13F holdings sum to 108.6% of shares outstanding. Readings above 100% reflect securities-lending double counting: shares on loan to short sellers are reported long by both the lending institution and the one that bought them. FINRA short interest of 4,865,616 shares (settlement 2026-05-15) accounts for the excess.
Filers outside the free window show locked, not hidden.