CIK: 0001222765
Total reported value
$895.6M
Reporting period: 2026-03-31 · Number of holdings: 98
WATER ISLAND CAPITAL LLC disclosed 98 holdings in its latest 13F filing for the period ending 2026-03-31, with total reported value of $895.6M and a quarterly turnover rate of 123.0%.
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Water Island Capital LLC's disclosed holdings carry a Herfindahl concentration index of 0.030 — mathematically equivalent to about 34 equally-sized positions, well below its 98 actual disclosed holdings. That gap points to a strategy built around a small core of high-conviction bets rather than broad diversification.
Position sizes vary widely across the portfolio (a coefficient of variation of 1.39), with a handful of outsized bets alongside many smaller positions.
No strong tilt toward either adding to existing winners or initiating outsized new positions was observed in the latest reported quarter.
Sector classification currently covers about 57% of this portfolio's disclosed value; the remainder includes holdings (e.g. unmapped tickers, options, or other security types) not yet covered by our sector mapping.
Add WBD
+1005.9% $26.1M
Trim SDA
-90.0% -$20.8M
Trim CWAN
-87.5% -$18.5M
Add JHG
+42.4% $16.6M
Add EA
+38.2% $14.0M
Trim AL
-75.5% -$14.4M
| # | Ticker | Issuer | Asset Subclass | Weight | Weight Change | Shares Change | 4Q Trend |
|---|---|---|---|---|---|---|---|
| 1 | EA | Electronic Arts INC | Stock-Comm Services | 5.69% | +1.71% | +38.18% | |
| 2 | JHG | Janus Henderson Group plc | Stock-Financials | 5.29% | +1.97% | +42.44% | |
| 3 | WBD | Warner Bros Discovery INC | Stock-Comm Services | 4.96% | +1.42% | +41.89% | |
| 4 | HO1 | Hologic INC | Stock-Other | 4.73% | — | +19.73% | |
| 5 | TXNM | Txnm Energy INC | Stock-Utilities | 4.40% | — | +17.08% | |
| 6 | PEN | Penumbra INC | Stock-Healthcare | 4.40% | +4.40% | NEW | |
| 7 | GTLS | Chart Industries INC | Stock-Industrials | 4.38% | — | +0.86% | |
| 8 | NSC | Norfolk Southern CORP | Stock-Industrials | 4.30% | — | +3.88% | |
| 9 | MASI* | Masimo CORP | Stock-Other | 3.86% | +3.86% | NEW | |
| 10 | EA | Electronic Arts Inc. | Stock-Comm Services | 3.41% | +3.41% | NEW | |
| 11 | WBS | Webster Financial CORP | Stock-Financials | 3.22% | +3.22% | NEW | |
| 12 | WBD | Warner Bros. Discovery, Inc. | Stock-Comm Services | 3.22% | +2.93% | +1005.90% | |
| 13 | T86 | Tri Pointe Homes INC | Stock-Other | 2.80% | +2.80% | NEW | |
| 14 | NSA | National Storage Affiliates | Stock-Real Estate | 2.43% | +2.43% | NEW | |
| 15 | GLDD | Great Lakes Dredge & Dock Co | Stock-Other | 2.40% | +2.40% | NEW | |
| 16 | ACLXGBX | Arcellx INC | Stock-Other | 2.35% | +2.35% | NEW | |
| 17 | DAWNGBX | Day One Biopharmaceuticals I | Stock-Other | 2.26% | +2.26% | NEW | |
| 18 | DBRG | Digitalbridge Group INC | Stock-Financials | 2.24% | — | +39.83% | |
| 19 | ✓ | Day One Biopharmaceuticals I | Stock-Other | 2.01% | +2.01% | NEW | |
| 20 | STEL | Stellar Bancorp INC | Stock-Other | 1.76% | +1.76% | NEW | |
| 21 | EHABUSD | Enhabit INC | Stock-Other | 1.55% | +1.55% | NEW | |
| 22 | SLAB | Silicon Laboratories INC | Stock-Tech | 1.36% | +1.36% | NEW | |
| 23 | KVUE | Kenvue INC | Stock-Consumer Staples | 1.35% | — | +1.51% | |
| 24 | ✓ | Kenvue INC | Stock-Other | 1.35% | — | +0.81% | |
| 25 | VRSK | Verisk Analytics, Inc. | Stock-Industrials | 1.26% | +1.26% | NEW | |
| 26 | PKST | Peakstone Realty Trust | Stock-Other | 1.17% | +1.17% | NEW | |
| 27 | ✓ | Terns Pharmaceuticals INC | Stock-Other | 1.11% | +1.11% | NEW | |
| 28 | 430 | Terns Pharmaceuticals INC | Stock-Other | 1.11% | +1.11% | NEW | |
| 29 | ✓ | Silicon Laboratories INC | Stock-Other | 1.11% | +1.11% | NEW | |
| 30 | ✓ | Stock-Other | 1.00% | +1.00% | NEW | ||
| 31 | ZIM | ZIM Integrated Shipping Services Ltd. | Stock-Other | 0.98% | — | — | |
| 32 | ✓ | Zim Integrated Shipping Serv | Stock-Other | 0.98% | +0.98% | NEW | |
| 33 | TXNM 5.75 06-01-54 | Txnm Energy INC | Stock-Utilities | 0.90% | — | +100.00% | |
| 34 | ✓ | Janus Henderson Group PLC | Stock-Other | 0.88% | — | +1185.83% | |
| 35 | ✓ | Banco Santander S.a. | Stock-Other | 0.86% | — | — | |
| 36 | UNF | Unifirst Corp/ma | Stock-Other | 0.72% | — | — | |
| 37 | CSGS 3.875 09-15-28 | Csg Systems Internationa | Stock-Other | 0.68% | — | — | |
| 38 | AXTA | Axalta Coating Systems Ltd. | Stock-Materials | 0.64% | — | +0.57% | |
| 39 | ✓ | Axalta Coating Sys LTD | Stock-Other | 0.60% | — | +190.61% | |
| 40 | RPD 0.25 03-15-27 | Rapid7 INC | Stock-Other | 0.54% | — | — | |
| 41 | APLSUSD | Apellis Pharmaceuticals INC | Stock-Other | 0.54% | — | — | |
| 42 | ✓ | Apellis Pharmaceuticals INC | Stock-Other | 0.54% | — | — | |
| 43 | AL | Air Lease CORP | Stock-Other | 0.53% | -1.54% | -75.50% | |
| 44 | BSY 0.375 07-01-27 | Bentley Systems | Stock-Tech | 0.53% | — | — | |
| 45 | NTNX 0.5 12-15-29 | Nutanix INC | Stock-Tech | 0.50% | — | +42.86% | |
| 46 | RDFN 0.5 04-01-27 | Redfin CORP | Stock-Other | 0.48% | — | — | |
| 47 | HALO 0.25 03-01-27 | Halozyme Therapeutics In | Stock-Healthcare | 0.35% | — | — | |
| 48 | AES | Aes CORP | Stock-Utilities | 0.29% | — | — | |
| 49 | VRNS 1 09-15-29 | Varonis System INC | Stock-Tech | 0.29% | — | — | |
| 50 | CWAN | Clearwater Analytics Holdings, Inc. | Stock-Tech | 0.29% | -1.99% | -87.48% |
Performance for Q3 2026
—
Performance Last 4 Quarters
—
Based on 0 months of available history
Based on 33% of reported portfolio value with available pricing
| Period | Holdings | Total value | Stability | Top holdings |
|---|---|---|---|---|
| 2026-03-31 | 98 | $895.6M | 100 | |
| 2025-12-31 | 91 | $927.6M | 100 | |
| 2025-09-30 | 84 | $793.3M | 100 | |
| 2025-06-30 | 76 | $702.0M | 0 | |
| 2025-03-31 | 84 | $764.1M | 100 | |
| 2024-12-31 | 78 | $925.7M | 0 | |
| 2024-09-30 | 79 | $992.7M | 0 | |
| 2024-06-30 | 75 | $986.6M | 0 | |
| 2024-03-31 | 61 | $961.8M | 0 | |
| 2023-12-31 | 58 | $1.0B | 0 | |
| 2023-09-30 | 81 | $1.1B | 0 | |
| 2023-06-30 | 76 | $1.2B | — | |
| 2023-03-31 | 75 | $1.3B | — | |
| 2022-12-31 | 87 | $1.2B | — | |
| 2022-09-30 | 103 | $1.8B | 0 | |
| 2022-06-30 | 88 | $1.6B | 0 | |
| 2022-03-31 | 85 | $2.0B | 0 | |
| 2021-12-31 | 97 | $1.8B | 0 | |
| 2021-09-30 | 70 | $1.7B | 0 | |
| 2021-06-30 | 72 | $1.9B | 93 | |
| 2021-03-31 | 96 | $1.6B | 100 | |
| 2020-12-31 | 106 | $1.4B | 100 | |
| 2020-09-30 | 96 | $1.2B | 100 | |
| 2020-06-30 | 82 | $1.1B | 100 | |
| 2020-03-31 | 61 | $1.4B | 100 | |
| 2019-12-31 | 66 | $1.4B | 100 | |
| 2019-09-30 | 78 | $1.6B | 100 | |
| 2019-06-30 | 99 | $2.2B | 100 | |
| 2019-03-31 | 146 | $2.0B | 100 | |
| 2018-12-31 | 96 | $1.3B | 100 | |
| 2018-09-30 | 103 | $1.8B | 100 | |
| 2018-06-30 | 118 | $1.8B | 100 | |
| 2018-03-31 | 93 | $2.5B | 100 | |
| 2017-12-31 | 90 | $1.6B | 100 | |
| 2017-09-30 | 109 | $2.1B | 100 | |
| 2017-06-30 | 108 | $2.1B | 100 | |
| 2017-03-31 | 88 | $1.8B | 100 | 1H0153129662443920355 |
| 2016-12-31 | 113 | $1.5B | 100 | 1790849212646R3016404 |
| 2016-09-30 | 148 | $1.6B | 100 | 1465685253578A3790849 |
| 2016-06-30 | 192 | $2.0B | 100 | |
| 2016-03-31 | 169 | $1.5B | 100 | |
| 2015-12-31 | 115 | $1.9B | 100 | |
| 2015-09-30 | 105 | $2.0B | 100 | |
| 2015-06-30 | 104 | $2.5B | 100 | 125490A24410603583334 |
| 2015-03-31 | 138 | $2.7B | 100 | 187264s2795435325490a |
| 2014-12-31 | 106 | $3.0B | 100 | 1G2554F289674K3018490 |
| 2014-09-30 | 191 | $2.9B | 100 | 1h27178287311l302917r |
| 2014-06-30 | 102 | $2.9B | 100 | 134583829031193786514 |
| 2014-03-31 | 91 | $2.8B | 100 | |
| 2013-12-31 | 75 | $1.8B | 100 | |
| 2013-09-30 | 62 | $2.6B | 100 | |
| 2013-06-30 | 59 | $2.1B | 0 |
Water Island Capital LLC's most significant position changes for 2026-03-31: New buy: Penumbra INC (PEN); Sold out: Cyberark Software LTD; Sold out: Exact Sciences CORP (EXK); Sold out: Comerica INC (CMA); New buy: Masimo CORP (MASI*).
| # | Ticker | Issuer | Weight Change | Shares Change | Action |
|---|---|---|---|---|---|
| 1 | WBD | Warner Bros. Discovery, Inc. | +2.9% | +1005.90% | Add |
| 2 | JHG | Janus Henderson Group plc | +2% | +42.44% | Add |
| 3 | EA | Electronic Arts INC | +1.7% | +38.18% | Add |
| 4 | WBD | Warner Bros Discovery INC | +1.4% | +41.89% | Add |
| 5 | ✓ | Csg Systems International In | -1.1% | -86.58% | Trim |
| 6 | AL | Air Lease CORP | -1.5% | -75.50% | Trim |
| 7 | CWAN | Clearwater Analytics Holdings, Inc. | -2% | -87.48% | Trim |
| 8 | SDA | Sealed Air CORP | -2.2% | -89.97% | Trim |
| 9 | PEN | Penumbra INC | — | NEW | New buy |
| 10 | ✓ | Cyberark Software LTD | — | EXIT | Sold out |
| 11 | EXK | Exact Sciences CORP | — | EXIT | Sold out |
| 12 | CMA | Comerica INC | — | EXIT | Sold out |
| 13 | MASI* | Masimo CORP | — | NEW | New buy |
| 14 | CDTX | Cidara Therapeutics INC | — | EXIT | Sold out |
| 15 | EA | Electronic Arts Inc. | — | NEW | New buy |
| 16 | WBS | Webster Financial CORP | — | NEW | New buy |
| 17 | T86 | Tri Pointe Homes INC | — | NEW | New buy |
| 18 | ✓ | Avadel Pharmaceu | — | EXIT | Sold out |
| 19 | TGNA | Tegna INC | — | EXIT | Sold out |
| 20 | NSA | National Storage Affiliates | — | NEW | New buy |
| 21 | GLDD | Great Lakes Dredge & Dock Co | — | NEW | New buy |
| 22 | AHL-PD | Aspen Insurance Holdings Limited | — | EXIT | Sold out |
| 23 | ACLXGBX | Arcellx INC | — | NEW | New buy |
| 24 | DAWNGBX | Day One Biopharmaceuticals I | — | NEW | New buy |
| 25 | SYU1 | Synovus Financial CORP | — | EXIT | Sold out |
| 26 | 8QR | Confluent Inc-class A | — | EXIT | Sold out |
| 27 | ✓ | Day One Biopharmaceuticals I | — | NEW | New buy |
| 28 | SPY | State Street SPDR S&P 500 ETF Trust | — | EXIT | Sold out |
| 29 | ✓ | Cidara Therapeutics INC | — | EXIT | Sold out |
| 30 | STEL | Stellar Bancorp INC | — | NEW | New buy |
| 31 | TECK | Teck Resources Limited | — | EXIT | Sold out |
| 32 | EHABUSD | Enhabit INC | — | NEW | New buy |
| 33 | JAMF | Jamf Holding CORP | — | EXIT | Sold out |
| 34 | CADE | Cadence Bank | — | EXIT | Sold out |
| 35 | 9HI | Hillenbrand INC | — | EXIT | Sold out |
| 36 | PLYM | Plymouth Industrial Reit INC | — | EXIT | Sold out |
| 37 | ✓ | Avidity Biosciences INC | — | EXIT | Sold out |
| 38 | SLAB | Silicon Laboratories INC | — | NEW | New buy |
| 39 | RNAGBP | Avidity Biosciences INC | — | EXIT | Sold out |
| 40 | VRSK | Verisk Analytics, Inc. | — | NEW | New buy |
| 41 | PKST | Peakstone Realty Trust | — | NEW | New buy |
| 42 | ✓ | Hillenbrand INC | — | EXIT | Sold out |
| 43 | 430 | Terns Pharmaceuticals INC | — | NEW | New buy |
| 44 | ✓ | Terns Pharmaceuticals INC | — | NEW | New buy |
| 45 | ✓ | Silicon Laboratories INC | — | NEW | New buy |
| 46 | DVAX | Dynavax Technologies CORP | — | EXIT | Sold out |
| 47 | QRVO | Qorvo INC | — | EXIT | Sold out |
| 48 | ✓ | — | NEW | New buy | |
| 49 | FRGE | Forge Global Holdings INC | — | EXIT | Sold out |
| 50 | ✓ | Zim Integrated Shipping Serv | — | NEW | New buy |
| Period | Filed | Type | EDGAR |
|---|---|---|---|
| 2026-03-31 | 2026-05-15 | 13F-HR | View on EDGAR |
| 2025-12-31 | 2026-02-17 | 13F-HR | View on EDGAR |
| 2025-09-30 | 2025-11-14 | 13F-HR | View on EDGAR |
| 2025-06-30 | 2025-08-14 | 13F-HR | View on EDGAR |
| 2025-03-31 | 2025-05-15 | 13F-HR | View on EDGAR |
| 2024-12-31 | 2025-02-13 | 13F-HR | View on EDGAR |
| 2024-09-30 | 2024-11-14 | 13F-HR | View on EDGAR |
| 2024-06-30 | 2024-11-14 | Amendment | View on EDGAR |
| 2024-06-30 | 2024-08-15 | 13F-HR | View on EDGAR |
| 2024-03-31 | 2024-11-14 | Amendment | View on EDGAR |
| 2024-03-31 | 2024-05-15 | 13F-HR | View on EDGAR |
| 2023-12-31 | 2024-11-14 | Amendment | View on EDGAR |
| 2023-12-31 | 2024-02-13 | 13F-HR | View on EDGAR |
| 2023-09-30 | 2024-11-14 | Amendment | View on EDGAR |
| 2023-09-30 | 2023-11-14 | 13F-HR | View on EDGAR |
| 2023-06-30 | 2024-11-14 | Amendment | View on EDGAR |
| 2023-06-30 | 2023-08-14 | 13F-HR | View on EDGAR |
| 2023-03-31 | 2024-11-14 | Amendment | View on EDGAR |
| 2023-03-31 | 2023-05-25 | 13F-HR | View on EDGAR |
| 2022-12-31 | 2024-11-14 | Amendment | View on EDGAR |
| 2022-12-31 | 2023-02-14 | 13F-HR | View on EDGAR |
| 2022-09-30 | 2022-11-14 | 13F-HR | View on EDGAR |
| 2022-06-30 | 2022-08-15 | 13F-HR | View on EDGAR |
| 2022-03-31 | 2022-05-13 | 13F-HR | View on EDGAR |
| 2021-12-31 | 2022-02-14 | 13F-HR | View on EDGAR |
| 2021-09-30 | 2021-11-12 | 13F-HR | View on EDGAR |
| 2021-06-30 | 2021-08-12 | 13F-HR | View on EDGAR |
| 2021-03-31 | 2021-05-13 | 13F-HR | View on EDGAR |
| 2020-12-31 | 2021-02-10 | 13F-HR | View on EDGAR |
| 2020-09-30 | 2020-11-12 | 13F-HR | View on EDGAR |
| 2020-06-30 | 2020-08-12 | 13F-HR | View on EDGAR |
| 2020-03-31 | 2020-05-12 | 13F-HR | View on EDGAR |
| 2019-12-31 | 2020-02-11 | 13F-HR | View on EDGAR |
| 2019-09-30 | 2019-11-12 | 13F-HR | View on EDGAR |
| 2019-06-30 | 2019-09-13 | Amendment | View on EDGAR |
| 2019-06-30 | 2019-08-12 | 13F-HR | View on EDGAR |
| 2019-03-31 | 2019-05-07 | Amendment | View on EDGAR |
| 2019-03-31 | 2019-05-03 | 13F-HR | View on EDGAR |
| 2018-12-31 | 2019-02-05 | 13F-HR | View on EDGAR |
| 2018-09-30 | 2018-11-13 | 13F-HR | View on EDGAR |
| 2018-06-30 | 2018-08-09 | 13F-HR | View on EDGAR |
| 2018-03-31 | 2018-05-14 | 13F-HR | View on EDGAR |
| 2017-12-31 | 2018-02-13 | 13F-HR | View on EDGAR |
| 2017-09-30 | 2017-11-14 | 13F-HR | View on EDGAR |
| 2017-06-30 | 2017-08-14 | 13F-HR | View on EDGAR |
| 2017-03-31 | 2017-05-15 | 13F-HR | View on EDGAR |
| 2016-12-31 | 2017-02-14 | 13F-HR | View on EDGAR |
| 2016-09-30 | 2016-11-17 | 13F-HR | View on EDGAR |
| 2016-06-30 | 2016-08-15 | 13F-HR | View on EDGAR |
| 2016-03-31 | 2016-05-16 | Amendment | View on EDGAR |
| 2016-03-31 | 2016-05-16 | 13F-HR | View on EDGAR |
| 2015-12-31 | 2016-02-16 | 13F-HR | View on EDGAR |
| 2015-09-30 | 2016-01-04 | Amendment | View on EDGAR |
| 2015-09-30 | 2015-11-13 | 13F-HR | View on EDGAR |
| 2015-06-30 | 2015-08-14 | 13F-HR | View on EDGAR |
| 2015-03-31 | 2015-05-13 | 13F-HR | View on EDGAR |
| 2014-12-31 | 2015-02-10 | Amendment | View on EDGAR |
| 2014-12-31 | 2015-02-10 | 13F-HR | View on EDGAR |
| 2014-09-30 | 2014-11-12 | Amendment | View on EDGAR |
| 2014-09-30 | 2014-11-10 | 13F-HR | View on EDGAR |
| 2014-06-30 | 2014-08-13 | 13F-HR | View on EDGAR |
| 2014-03-31 | 2014-05-14 | 13F-HR | View on EDGAR |
| 2013-12-31 | 2014-02-14 | 13F-HR | View on EDGAR |
| 2013-09-30 | 2013-11-14 | 13F-HR | View on EDGAR |
| 2013-06-30 | 2013-08-14 | Amendment | View on EDGAR |
| 2013-06-30 | 2013-08-09 | 13F-HR | View on EDGAR |
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