# WESTFIELD CAPITAL MANAGEMENT CO LP

> Institutional holdings reported to the SEC as of Q2 2026 on Form 13F. CIK 1177719. Source: https://holderbook.com/funds/1177719-westfield-capital-management-co-lp/

- Reported value: $30.6B
- Positions: 278
- Weight of the ten largest: 29.2%
- Filed: 2026-08-12

A 13F reports long US equity positions only. Short positions, bonds, foreign listings, private holdings and cash are not visible, so this is not the manager's whole book.

## Holdings

| Security | Ticker | Value | Shares | Weight | Quarters held |
|---|---|---|---|---|---|
| NVIDIA CORPORATION | [NVDA](https://holderbook.com/stocks/NVDA/) | $1.6B | 8,079,926 | 5.3% | 27 |
| ALPHABET INC | [GOOGL](https://holderbook.com/stocks/GOOGL/) | $1.3B | 3,749,074 | 4.4% | 31 |
| ASCENDIS PHARMA A/S | [ASND](https://holderbook.com/stocks/ASND/) | $1.3B | 4,798,267 | 4.2% | 1 |
| AXON ENTERPRISE INC | [AXON](https://holderbook.com/stocks/AXON/) | $836.1M | 1,491,490 | 2.7% | 15 |
| FTAI AVIATION LTD | [FTAI](https://holderbook.com/stocks/FTAI/) | $794.6M | 2,937,228 | 2.6% | 9 |
| APPLE INC | [AAPL](https://holderbook.com/stocks/AAPL/) | $744.7M | 2,573,774 | 2.4% | 31 |
| COMFORT SYS USA INC | [FIX](https://holderbook.com/stocks/FIX/) | $704.5M | 355,433 | 2.3% | 11 |
| BROADCOM INC | [AVGO](https://holderbook.com/stocks/AVGO/) | $588.0M | 1,556,522 | 1.9% | 31 |
| MICROSOFT CORP | [MSFT](https://holderbook.com/stocks/MSFT/) | $527.6M | 1,414,294 | 1.7% | 31 |
| HOWMET AEROSPACE INC | [HWM](https://holderbook.com/stocks/HWM/) | $516.6M | 1,921,476 | 1.7% | 6 |
| ELI LILLY & CO | [LLY](https://holderbook.com/stocks/LLY/) | $499.8M | 416,732 | 1.6% | 17 |
| SNOWFLAKE INC | [SNOW](https://holderbook.com/stocks/SNOW/) | $441.9M | 1,736,498 | 1.4% | 5 |
| MKS INC. | [MKSI](https://holderbook.com/stocks/MKSI/) | $413.0M | 928,617 | 1.3% | 4 |
| META PLATFORMS INC | [META](https://holderbook.com/stocks/META/) | $381.6M | 677,389 | 1.2% | 14 |
| VERTIV HOLDINGS CO | [VRT](https://holderbook.com/stocks/VRT/) | $353.0M | 1,054,361 | 1.2% | 12 |
| GE VERNOVA INC | [GEV](https://holderbook.com/stocks/GEV/) | $283.5M | 241,272 | 0.9% | 8 |
| MICRON TECHNOLOGY INC | [MU](https://holderbook.com/stocks/MU/) | $263.4M | 228,203 | 0.9% | 2 |
| VISA INC | [V](https://holderbook.com/stocks/V/) | $261.6M | 762,403 | 0.9% | 31 |
| API GROUP CORP | [APG](https://holderbook.com/stocks/APG/) | $260.6M | 6,154,301 | 0.9% | 3 |
| TAPESTRY INC | [TPR](https://holderbook.com/stocks/TPR/) | $248.3M | 1,696,569 | 0.8% | 22 |
| RHYTHM PHARMACEUTICALS INC | [RYTM](https://holderbook.com/stocks/RYTM/) | $245.2M | 2,208,595 | 0.8% | 6 |
| LIFE TIME GROUP HOLDINGS INC | [LTH](https://holderbook.com/stocks/LTH/) | $244.8M | 5,995,254 | 0.8% | 2 |
| TAIWAN SEMICONDUCTOR MANUFAC | [TSM](https://holderbook.com/stocks/TSM/) | $244.0M | 510,999 | 0.8% | 10 |
| GUARDANT HEALTH INC | [GH](https://holderbook.com/stocks/GH/) | $243.7M | 1,624,459 | 0.8% | 3 |
| QUANTA SVCS INC | [PWR](https://holderbook.com/stocks/PWR/) | $238.7M | 331,489 | 0.8% | 5 |
| SERVICENOW INC | [NOW](https://holderbook.com/stocks/NOW/) | $235.7M | 2,373,711 | 0.8% | 31 |
| ADVANCED MICRO DEVICES INC | [AMD](https://holderbook.com/stocks/AMD/) | $234.2M | 403,081 | 0.8% | 3 |
| PALO ALTO NETWORKS INC | [PANW](https://holderbook.com/stocks/PANW/) | $224.5M | 658,331 | 0.7% | 4 |
| WOODWARD INC | [WWD](https://holderbook.com/stocks/WWD/) | $224.0M | 526,505 | 0.7% | 2 |
| ARISTA NETWORKS INC | [ANET](https://holderbook.com/stocks/ANET/) | $223.7M | 1,317,096 | 0.7% | 2 |
| LPL FINL HLDGS INC | [LPLA](https://holderbook.com/stocks/LPLA/) | $223.4M | 793,061 | 0.7% | 31 |
| ROCKET LAB CORP | [RKLB](https://holderbook.com/stocks/RKLB/) | $214.9M | 2,114,005 | 0.7% | 5 |
| AMER SPORTS INC | [AS](https://holderbook.com/stocks/AS/) | $214.7M | 6,344,923 | 0.7% | 2 |
| CLOUDFLARE INC | [NET](https://holderbook.com/stocks/NET/) | $204.9M | 835,502 | 0.7% | 5 |
| AMAZON COM INC | [AMZN](https://holderbook.com/stocks/AMZN/) | $204.9M | 859,806 | 0.7% | 31 |
| GARMIN LTD | [GRMN](https://holderbook.com/stocks/GRMN/) | $204.5M | 861,057 | 0.7% | 3 |
| REGAL REXNORD CORPORATION | [RRX](https://holderbook.com/stocks/RRX/) | $204.1M | 856,976 | 0.7% | 11 |
| NATERA INC | [NTRA](https://holderbook.com/stocks/NTRA/) | $197.2M | 726,628 | 0.6% | 7 |
| MORGAN STANLEY | [MS](https://holderbook.com/stocks/MS/) | $196.6M | 940,560 | 0.6% | 2 |
| CARPENTER TECHNOLOGY CORP | [CRS](https://holderbook.com/stocks/CRS/) | $193.7M | 314,082 | 0.6% | 1 |
| SAMSARA INC | [IOT](https://holderbook.com/stocks/IOT/) | $189.3M | 5,836,459 | 0.6% | 19 |
| DYNATRACE INC | [DT](https://holderbook.com/stocks/DT/) | $186.6M | 4,249,229 | 0.6% | 15 |
| CATERPILLAR INC | [CAT](https://holderbook.com/stocks/CAT/) | $186.0M | 174,620 | 0.6% | 2 |
| SEMTECH CORP | [SMTC](https://holderbook.com/stocks/SMTC/) | $183.4M | 1,133,268 | 0.6% | 6 |
| AMETEK INC | [AME](https://holderbook.com/stocks/AME/) | $175.1M | 723,798 | 0.6% | 31 |
| ABIVAX SA | [ABVX](https://holderbook.com/stocks/ABVX/) | $174.5M | 1,309,825 | 0.6% | 3 |
| INSMED INC | [INSM](https://holderbook.com/stocks/INSM/) | $173.7M | 1,629,561 | 0.6% | 8 |
| ITT INC | [ITT](https://holderbook.com/stocks/ITT/) | $164.2M | 830,382 | 0.5% | 25 |
| GILEAD SCIENCES INC | [GILD](https://holderbook.com/stocks/GILD/) | $162.7M | 1,287,629 | 0.5% | 3 |
| PTC THERAPEUTICS INC | [PTCT](https://holderbook.com/stocks/PTCT/) | $159.6M | 1,956,156 | 0.5% | 1 |
| DUTCH BROS INC | [BROS](https://holderbook.com/stocks/BROS/) | $156.8M | 2,184,001 | 0.5% | 3 |
| CELSIUS HLDGS INC | [CELH](https://holderbook.com/stocks/CELH/) | $155.9M | 5,324,481 | 0.5% | 3 |
| MASTEC INC | [MTZ](https://holderbook.com/stocks/MTZ/) | $155.8M | 374,457 | 0.5% | 2 |
| SHARKNINJA INC | [SN](https://holderbook.com/stocks/SN/) | $153.5M | 1,008,349 | 0.5% | 8 |
| CSX CORP | [CSX](https://holderbook.com/stocks/CSX/) | $149.9M | 3,154,419 | 0.5% | 31 |
| FIRSTCASH HOLDINGS INC | [FCFS](https://holderbook.com/stocks/FCFS/) | $149.9M | 693,085 | 0.5% | 4 |
| KEYCORP | [KEY](https://holderbook.com/stocks/KEY/) | $149.7M | 6,493,467 | 0.5% | 10 |
| MICROCHIP TECHNOLOGY INC. | [MCHP](https://holderbook.com/stocks/MCHP/) | $149.5M | 1,639,111 | 0.5% | 2 |
| APPLIED MATLS INC | [AMAT](https://holderbook.com/stocks/AMAT/) | $148.6M | 205,592 | 0.5% | 3 |
| MARRIOTT INTL INC NEW | [MAR](https://holderbook.com/stocks/MAR/) | $147.9M | 398,962 | 0.5% | 2 |
| VAXCYTE INC | [PCVX](https://holderbook.com/stocks/PCVX/) | $143.7M | 2,472,428 | 0.5% | 12 |
| GLOBE LIFE INC | [GL](https://holderbook.com/stocks/GL/) | $137.8M | 770,990 | 0.4% | 4 |
| TECHNIPFMC PLC | [FTI](https://holderbook.com/stocks/FTI/) | $136.6M | 2,059,689 | 0.4% | 8 |
| XPO INC | [XPO](https://holderbook.com/stocks/XPO/) | $129.1M | 629,011 | 0.4% | 5 |
| LEGEND BIOTECH CORP | [LEGN](https://holderbook.com/stocks/LEGN/) | $127.9M | 4,430,063 | 0.4% | 13 |
| EVERPURE INC | [P](https://holderbook.com/stocks/P/) | $127.0M | 1,611,958 | 0.4% | 9 |
| LAM RESEARCH CORP | [LRCX](https://holderbook.com/stocks/LRCX/) | $123.8M | 285,614 | 0.4% | 1 |
| JONES LANG LASALLE INC | [JLL](https://holderbook.com/stocks/JLL/) | $123.5M | 398,453 | 0.4% | 2 |
| ASTERA LABS INC | [ALAB](https://holderbook.com/stocks/ALAB/) | $120.4M | 249,299 | 0.4% | 4 |
| ROCKWELL AUTOMATION INC | [ROK](https://holderbook.com/stocks/ROK/) | $117.4M | 237,136 | 0.4% | 31 |
| IDEX CORP | [IEX](https://holderbook.com/stocks/IEX/) | $116.6M | 513,564 | 0.4% | 26 |
| COHERENT CORP | [COHR](https://holderbook.com/stocks/COHR/) | $114.8M | 291,040 | 0.4% | 6 |
| LEGENCE CORP | [LGN](https://holderbook.com/stocks/LGN/) | $114.4M | 1,341,963 | 0.4% | 3 |
| LINCOLN ELEC HLDGS INC | [LECO](https://holderbook.com/stocks/LECO/) | $114.4M | 430,681 | 0.4% | 31 |
| ASML HLDG NV | [ASML](https://holderbook.com/stocks/ASML/) | $114.3M | 57,430 | 0.4% | 1 |
| PLANET LABS PBC | [PL](https://holderbook.com/stocks/PL/) | $113.6M | 3,428,007 | 0.4% | 2 |
| ONTO INNOVATION INC | [ONTO](https://holderbook.com/stocks/ONTO/) | $113.3M | 299,383 | 0.4% | 7 |
| CENCORA INC | [COR](https://holderbook.com/stocks/COR/) | $113.2M | 400,058 | 0.4% | 6 |
| REVOLUTION MEDICINES INC | [RVMD](https://holderbook.com/stocks/RVMD/) | $112.5M | 600,821 | 0.4% | 7 |
| SANDISK CORP | [SNDK](https://holderbook.com/stocks/SNDK/) | $111.5M | 49,024 | 0.4% | 1 |
| AFFIRM HLDGS INC | [AFRM](https://holderbook.com/stocks/AFRM/) | $110.3M | 1,352,200 | 0.4% | 5 |
| LIVE NATION ENTERTAINMENT IN | [LYV](https://holderbook.com/stocks/LYV/) | $108.2M | 590,764 | 0.4% | 7 |
| ENPRO INC | [NPO](https://holderbook.com/stocks/NPO/) | $108.0M | 286,554 | 0.4% | 1 |
| PERMIAN RESOURCES CORP | [PR](https://holderbook.com/stocks/PR/) | $106.0M | 5,756,888 | 0.3% | 12 |
| ARES MANAGEMENT CORPORATION | [ARES](https://holderbook.com/stocks/ARES/) | $106.0M | 952,032 | 0.3% | 20 |
| IMAX CORP | [IMAX](https://holderbook.com/stocks/IMAX/) | $105.8M | 2,654,014 | 0.3% | 4 |
| GUIDEWIRE SOFTWARE INC | [GWRE](https://holderbook.com/stocks/GWRE/) | $103.3M | 839,337 | 0.3% | 2 |
| NEXTPOWER INC | [NXT](https://holderbook.com/stocks/NXT/) | $102.2M | 857,399 | 0.3% | 11 |
| JFROG LTD | [FROG](https://holderbook.com/stocks/FROG/) | $101.3M | 1,114,561 | 0.3% | 1 |
| SYNOPSYS INC | [SNPS](https://holderbook.com/stocks/SNPS/) | $101.2M | 226,856 | 0.3% | 5 |
| ROKU INC | [ROKU](https://holderbook.com/stocks/ROKU/) | $99.0M | 716,557 | 0.3% | 9 |
| PLEXUS CORP | [PLXS](https://holderbook.com/stocks/PLXS/) | $96.8M | 321,808 | 0.3% | 12 |
| APPLIED INDL TECHNOLOGIES IN | [AIT](https://holderbook.com/stocks/AIT/) | $96.6M | 285,691 | 0.3% | 8 |
| MSCI INC | [MSCI](https://holderbook.com/stocks/MSCI/) | $96.3M | 171,958 | 0.3% | 31 |
| ROBINHOOD MKTS INC | [HOOD](https://holderbook.com/stocks/HOOD/) | $95.8M | 955,544 | 0.3% | 6 |
| ROSS STORES INC | [ROST](https://holderbook.com/stocks/ROST/) | $94.2M | 442,420 | 0.3% | 2 |
| ADAPTIVE BIOTECHNOLOGIES COR | [ADPT](https://holderbook.com/stocks/ADPT/) | $91.5M | 4,267,645 | 0.3% | 3 |
| XENON PHARMACEUTICALS INC | [XENE](https://holderbook.com/stocks/XENE/) | $91.0M | 1,507,294 | 0.3% | 11 |
| OREILLY AUTOMOTIVE INC | [ORLY](https://holderbook.com/stocks/ORLY/) | $85.9M | 933,255 | 0.3% | 5 |
| CITIGROUP INC | [C](https://holderbook.com/stocks/C/) | $85.1M | 608,124 | 0.3% | 3 |

## What the disclosed book did

Not the fund's return. This is the change in value of the positions disclosed on Form 13F, had they been left untouched, against SPY over the same quarter ends.

| Quarter | Book | Market | Difference | Priced |
|---|---|---|---|---|
| Q2 2026 | +22.3% | +14.8% | +7.5% | 100% |
| Q1 2026 | -2.8% | -4.6% | +1.8% | 100% |
| Q4 2025 | +1.6% | +2.4% | -0.8% | 100% |
| Q3 2025 | +5.5% | +7.8% | -2.4% | 100% |
| Q2 2025 | +17.5% | +10.5% | +7.0% | 100% |
| Q1 2025 | -10.1% | -4.6% | -5.5% | 100% |
| Q4 2024 | +4.0% | +2.1% | +1.9% | 100% |
| Q3 2024 | +6.3% | +5.4% | +0.9% | 100% |

## Quarter by quarter

| Quarter | Value | Positions |
|---|---|---|
| Q2 2026 | $30.6B | 278 |
| Q1 2026 | $23.8B | 250 |
| Q4 2025 | $24.0B | 241 |
| Q3 2025 | $23.8B | 235 |
| Q2 2025 | $23.8B | 239 |
| Q1 2025 | $20.5B | 244 |
| Q4 2024 | $23.0B | 239 |
| Q3 2024 | $22.1B | 247 |
| Q2 2024 | $20.4B | 248 |
| Q1 2024 | $19.0B | 244 |
| Q4 2023 | $17.2B | 239 |
| Q3 2023 | $14.7B | 234 |