Westfield Capital Management Co LP
Reported US equity positions for Q1 2026 — $23.8B across 250 positions.
| Holding | Reported value | Share of portfolio | Shares |
|---|---|---|---|
| NVDA NVIDIA Corporation | $1.1B | 4.6% | 6,317,039 |
| 04351P101 Ascendis Pharma A/S | $1.1B | 4.6% | 4,813,440 |
| FIX Comfort Systems USA, Inc. | $856.2M | 3.6% | 620,915 |
| AAPL Apple Inc. | $795.2M | 3.3% | 3,133,113 |
| G3730V105 Ftai Aviation LTD | $697.8M | 2.9% | 2,848,227 |
| MSFT Microsoft Corporation | $610.6M | 2.6% | 1,649,513 |
| GOOGL Alphabet Inc. | $582.8M | 2.4% | 2,026,744 |
| HWM Howmet Aerospace Inc. | $527.7M | 2.2% | 2,289,697 |
| VRT Vertiv Holdings, LLC Class A | $481.5M | 2.0% | 1,921,696 |
| AMZN Amazon.com, Inc. | $474.8M | 2.0% | 2,279,654 |
| AXON Axon Enterprise, Inc. | $451.9M | 1.9% | 1,064,134 |
| AVGO Broadcom Inc. | $382.8M | 1.6% | 1,236,925 |
| LLY Eli Lilly and Company | $335.3M | 1.4% | 364,579 |
| TPR Tapestry, Inc. | $310.3M | 1.3% | 2,198,862 |
| META Meta Platforms, Inc. | $301.4M | 1.3% | 526,822 |
| LPLA LPL Financial Holdings Inc. | $265.2M | 1.1% | 881,506 |
| MKSI MKS Inc. | $240.6M | 1.0% | 1,046,763 |
| INSM Insmed Incorporated | $240.1M | 1.0% | 1,468,459 |
| PCVX Vaxcyte, Inc. | $211.9M | 0.9% | 3,646,138 |
| RKLB Rocket Lab Corporation | $203.7M | 0.9% | 3,172,611 |
| NFLX Netflix, Inc. | $189.4M | 0.8% | 1,969,994 |
| APG APi Group Corporation | $187.8M | 0.8% | 4,634,929 |
| PWR Quanta Services, Inc. | $182.2M | 0.8% | 331,816 |
| GEV GE Vernova Inc. | $174.0M | 0.7% | 199,306 |
| ARES Ares Management Corporation Class A | $171.6M | 0.7% | 1,572,787 |
| RYTM Rhythm Pharmaceuticals, Inc. | $167.8M | 0.7% | 1,929,123 |
| TSM Taiwan Semiconductor Manufacturing Company Ltd. | $166.8M | 0.7% | 493,504 |
| MRVL Marvell Technology, Inc. | $165.7M | 0.7% | 1,673,381 |
| BE Bloom Energy Corporation Class A | $161.4M | 0.7% | 1,191,572 |
| IOT Samsara Inc. Class A | $160.8M | 0.7% | 5,072,821 |
| AME AMETEK, Inc. | $159.9M | 0.7% | 745,832 |
| PR Permian Resources Corporation Class A | $159.5M | 0.7% | 7,481,457 |
| DT Dynatrace, Inc. | $155.7M | 0.7% | 4,209,594 |
| RVMD Revolution Medicines, Inc. | $151.4M | 0.6% | 1,556,578 |
| NTRA Natera, Inc. | $150.9M | 0.6% | 754,729 |
| G3323L100 Fabrinet | $148.6M | 0.6% | 284,874 |
| ABVX Abivax SA | $147.3M | 0.6% | 1,322,938 |
| NOW ServiceNow, Inc. | $145.8M | 0.6% | 1,394,187 |
| G87110105 Technipfmc PLC | $140.6M | 0.6% | 2,033,755 |
| V7780T103 Royal Caribbean Group | $139.2M | 0.6% | 505,765 |
| HLT Hilton Worldwide Holdings Inc. | $139.1M | 0.6% | 457,425 |
| V Visa Inc. | $138.0M | 0.6% | 456,548 |
| ABG Asbury Automotive Group Inc | $137.3M | 0.6% | 436,909 |
| ITT ITT Inc. | $134.0M | 0.6% | 703,309 |
| CELH Celsius Holdings, Inc. | $133.7M | 0.6% | 3,768,911 |
| NXT Nextpower Inc. | $133.5M | 0.6% | 1,107,346 |
| LNG Cheniere Energy, Inc. | $130.3M | 0.5% | 459,044 |
| G0260P102 Amer Sports INC | $129.6M | 0.5% | 3,937,521 |
| RRX Regal Rexnord Corporation | $127.7M | 0.5% | 681,717 |
| MSCI MSCI Inc. | $126.0M | 0.5% | 233,764 |
| GH Guardant Health, Inc. | $125.9M | 0.5% | 1,362,539 |
| LYV Live Nation Entertainment, Inc. | $123.6M | 0.5% | 810,710 |
| TSLA Tesla, Inc. | $117.5M | 0.5% | 316,102 |
| GL Globe Life Inc. | $117.2M | 0.5% | 842,423 |
| BROS Dutch Bros Inc. Class A | $117.2M | 0.5% | 2,313,357 |
| NET Cloudflare, Inc. Class A | $111.7M | 0.5% | 541,566 |
| ROKU Roku, Inc. | $111.5M | 0.5% | 1,178,219 |
| XPO XPO, Inc. | $111.3M | 0.5% | 571,992 |
| FITB Fifth Third Bancorp | $110.8M | 0.5% | 2,385,422 |
| P Everpure, Inc. Class A | $110.7M | 0.5% | 1,874,763 |
Long US equity positions only, as filed. 13F does not cover short positions, cash, bonds or non-US listings, so this is not the whole portfolio.
What changed last quarter
| Holding | Change | Now | Was | Shares |
|---|---|---|---|---|
| NVDA NVIDIA Corporation | Add | $1.1B | $1.1B | +6% |
| 04351P101 Ascendis Pharma A/S | Trim | $1.1B | $1.1B | -7% |
| FIX Comfort Systems USA, Inc. | Trim | $856.2M | $624.2M | -7% |
| AAPL Apple Inc. | Trim | $795.2M | $890.2M | -4% |
| G3730V105 Ftai Aviation LTD | Add | $697.8M | $462.7M | +21% |
| MSFT Microsoft Corporation | Add | $610.6M | $784.1M | +2% |
| GOOGL Alphabet Inc. | Trim | $582.8M | $681.9M | -7% |
| HWM Howmet Aerospace Inc. | Add | $527.7M | $455.0M | +3% |
| VRT Vertiv Holdings, LLC Class A | Trim | $481.5M | $369.0M | -16% |
| AMZN Amazon.com, Inc. | Trim | $474.8M | $538.0M | -2% |
| AXON Axon Enterprise, Inc. | Add | $451.9M | $472.1M | +28% |
| AVGO Broadcom Inc. | Add | $382.8M | $385.0M | +11% |
| LLY Eli Lilly and Company | Add | $335.3M | $298.3M | +31% |
| TPR Tapestry, Inc. | Add | $310.3M | $268.1M | +5% |
| META Meta Platforms, Inc. | Trim | $301.4M | $432.5M | -20% |
| LPLA LPL Financial Holdings Inc. | Add | $265.2M | $223.4M | +41% |
| MKSI MKS Inc. | Add | $240.6M | $134.2M | +25% |
| INSM Insmed Incorporated | Add | $240.1M | $75.3M | +240% |
| PCVX Vaxcyte, Inc. | Add | $211.9M | $163.3M | +3% |
| RKLB Rocket Lab Corporation | Add | $203.7M | $180.8M | +22% |
| NFLX Netflix, Inc. | Add | $189.4M | $149.8M | +23% |
| APG APi Group Corporation | Add | $187.8M | $132.1M | +34% |
| PWR Quanta Services, Inc. | Add | $182.2M | $115.4M | +21% |
| GEV GE Vernova Inc. | Add | $174.0M | $116.3M | +12% |
| ARES Ares Management Corporation Class A | Add | $171.6M | $186.1M | +37% |
| RYTM Rhythm Pharmaceuticals, Inc. | Add | $167.8M | $135.6M | +52% |
| TSM Taiwan Semiconductor Manufacturing Company Ltd. | Add | $166.8M | $135.6M | +11% |
| MRVL Marvell Technology, Inc. | Trim | $165.7M | $165.5M | -14% |
| BE Bloom Energy Corporation Class A | Add | $161.4M | $99.5M | +4% |
| IOT Samsara Inc. Class A | Add | $160.8M | $140.2M | +28% |
| AME AMETEK, Inc. | Trim | $159.9M | $184.8M | -17% |
| PR Permian Resources Corporation Class A | Add | $159.5M | $83.5M | +26% |
| DT Dynatrace, Inc. | Add | $155.7M | $145.5M | +25% |
| RVMD Revolution Medicines, Inc. | Trim | $151.4M | $226.6M | -45% |
| NTRA Natera, Inc. | Add | $150.9M | $163.7M | +6% |
| G3323L100 Fabrinet | Add | $148.6M | $86.6M | +50% |
| ABVX Abivax SA | Add | $147.3M | $136.2M | +31% |
| NOW ServiceNow, Inc. | Trim | $145.8M | $226.2M | -6% |
| G87110105 Technipfmc PLC | Add | $140.6M | $87.0M | +4% |
| V7780T103 Royal Caribbean Group | Add | $139.2M | $125.1M | +13% |
New and exited positions are only shown for managers whose entire filed portfolio fits inside the positions stored here. For a manager filing more than that, a holding leaving the stored set is indistinguishable from a holding being sold, so those are reported as adds and trims only.
What a 13F is
Any institutional manager exercising discretion over more than $100 million in US-listed equities must file a Form 13F with the SEC within 45 days of each quarter end, listing what they held on the last day of that quarter. The threshold was set in 1975 and has never been raised, so the filer population now runs to several thousand.
The four things it does not tell you
- It is stale. A filing describes positions as of quarter end and can arrive 45 days later. A manager who sold everything in week one of the new quarter files the same document as one who held.
- Long US equities only. No short positions, no cash, no bonds, no commodities, no foreign listings. A fund that looks heavily long in a 13F may be hedged in instruments that never appear.
- Not the whole firm. Assets are reported by the entity with discretion, so one manager can file under several CIKs, and the figure here is what that entity reported.
- Confidential treatment exists. A manager can apply to delay disclosing a position while building it. Those holdings appear later, if at all.
Why the biggest filers are not the interesting ones
The largest managers by reported value are index providers — they hold nearly everything, in proportion to the indices they track, because clients asked them to. Reading their filings for conviction is a category error. The filings worth attention are concentrated ones, where a small number of positions make up most of the portfolio, since that reflects a decision rather than a mandate.
The share-of-portfolio column is the one to read for this. A position that is 15% of a fund says something; the same dollar amount at 0.2% of an index tracker does not.
Where this comes from
The SEC's own quarterly Form 13F structured data sets, parsed here rather than bought from a vendor. Holdings are identified in the filings by CUSIP, and the mapping from CUSIP to ticker is the awkward part — that identifier is licensed rather than public, so the mapping is resolved through OpenFIGI and built up over time. Around 95% of reported value currently sits on a resolved ticker; the rest shows its CUSIP.
The rest of the section is on the Markets overview — including insider transactions, which are the same idea at the individual level, and the correlation finder, where each ticker's page carries its institutional ownership.