WESTFIELD CAPITAL MANAGEMENT CO LP
Filing Date
Global Rank
#157
/ 8,232
▲ 94
Top Industry
Biotechnology
10.4%
3Y Alpha vs SPY
-1.7%
Period ended 2 months ago
Filed May 11, 2026 · 34d
24 quarters · since Mar 2020
Clone Performance
Jun 2023–Jun 2026 · vs SPYHypothetical growth of cloning every reported 13F position and rebalancing on each filing, indexed to the same start.
Cloned portfolio
+68.8%
SPY
+76.3%
Annualised alpha
-1.7%
Max drawdown
−25.7%
Estimate. 13F holdings are quarter-lagged and long-only, so the clone rebalances about 45 days after each period end — when the filing becomes public — and excludes options and short positions. Past performance does not predict future results.
Portfolio Concentration
243 positions · as of Mar 31, 2026 · Δ vs Sep 30, 2025Top Position
4.6%
−0.6 pts
Top 5
19.1%
−1.2 pts
Top 10
30.4%
−1.2 pts
HHI
142
Diversified−9
Portfolio Trend
24 quarters · across all stocks
Sector Breakdown
As of Mar 31, 2026| Sector | % Portfolio | Value |
|---|---|---|
| Technology | 28.5% | $6,775,203,452 |
| Industrials | 25.3% | $6,018,658,027 |
| Healthcare | 15.8% | $3,766,470,562 |
| Consumer Cyclical | 10.5% | $2,501,827,195 |
| Financial Services | 8.9% | $2,111,651,462 |
| Communication Services | 5.9% | $1,399,076,589 |
| Energy | 2.7% | $642,147,704 |
| Consumer Defensive | 0.9% | $217,580,314 |
| Basic Materials | 0.6% | $144,528,024 |
| Utilities | 0.5% | $127,757,381 |
| Real Estate | 0.4% | $106,069,305 |
Last Quarter's Activity
Export CSVAdded To
Positions the filer increased
25 positions
| Ticker | Company | Δ Shares | Shares | Value | Open |
|---|---|---|---|---|---|
| PR | Permian Resources Corp | +4,123,741 | 7,481,457 | $159,504,663 | |
| RIOT | Riot Platforms, Inc. | +2,149,853 | 3,499,880 | $43,258,516 | |
| BRZE | Braze, Inc. | +1,795,953 | 3,973,906 | $93,823,920 | |
| NFLX | Netflix Inc | +1,739,346 | 1,969,994 | $189,414,923 | |
| IOT | Samsara Inc. | +1,271,034 | 5,072,821 | $160,757,697 | |
| NOW | ServiceNow, Inc. | +1,134,185 | 1,394,187 | $145,762,250 | |
| IONQ | IonQ, Inc. | +1,006,121 | 1,373,788 | $39,606,308 | |
| INSM | INSMED Inc | +980,532 | 1,468,459 | $240,122,415 | |
| DT | Dynatrace, Inc. | +863,814 | 4,209,594 | $155,670,786 | |
| CALX | Calix, Inc | +862,005 | 1,546,101 | $75,743,487 | |
| RYTM | Rhythm Pharmaceuticals, Inc. | +860,119 | 1,929,123 | $167,775,827 | |
| WGS | GeneDx Holdings Corp. | +825,014 | 1,369,108 | $87,924,115 | |
| FITB | Fifth Third Bancorp | +765,474 | 2,385,422 | $110,826,706 | |
| TOST | Toast, Inc. | +756,568 | 1,790,873 | $47,476,043 | |
| RKLB | Rocket Lab Corp | +734,791 | 3,172,611 | $203,745,078 | |
| MKSI | Mks Inc | +723,399 | 1,046,763 | $240,556,605 | |
| FTAI | FTAI Aviation Ltd. | +717,986 | 2,848,227 | $697,815,615 | |
| IMAX | Imax Corp | +716,151 | 2,338,776 | $88,896,875 | |
| KEY | Keycorp /New/ | +713,120 | 5,193,334 | $104,126,346 | |
| ALAB | Astera Labs, Inc. | +667,499 | 860,113 | $94,268,384 | |
| KTOS | Kratos Defense & Security Solutions, Inc. | +557,330 | 1,563,146 | $110,217,424 | |
| FTI | TechnipFMC plc | +553,645 | 2,033,755 | $140,593,483 | |
| ARES | Ares Management Corp | +545,198 | 1,572,787 | $171,591,061 | |
| CRDO | Credo Technology Group Holding Ltd | +453,378 | 926,219 | $86,944,177 | |
| GL | Globe Life Inc. | +411,781 | 842,423 | $117,240,008 | |
| No positions match the current search. | |||||
Trimmed
Positions the filer reduced
25 positions
| Ticker | Company | Δ Shares | Shares | Value | Open |
|---|---|---|---|---|---|
| GENI | Genius Sports Ltd | −5,642,933 | 207,150 | $917,674 | |
| BAC | Bank Of America Corp /De/ | −2,794,218 | 1,066,885 | $52,010,643 | |
| DXCM | Dexcom Inc | −2,285,136 | 27,074 | $1,700,247 | |
| SMTC | Semtech Corp | −2,099,779 | 1,280,594 | $98,464,872 | |
| OPCH | Option Care Health, Inc. | −1,575,044 | 1,182,814 | $31,841,352 | |
| MASI | Masimo Corp | −1,078,021 | 341,229 | $60,694,402 | |
| COHR | Coherent Corp. | −1,076,319 | 396,644 | $94,484,567 | |
| HQY | Healthequity, Inc. | −1,003,810 | 712,848 | $59,572,707 | |
| RVMD | Revolution Medicines, Inc. | −957,389 | 1,556,578 | $151,377,210 | |
| MRVL | Marvell Technology, Inc. | −938,577 | 1,673,381 | $165,748,388 | |
| CWST | Casella Waste Systems Inc | −825,415 | 822,492 | $65,256,515 | |
| GKOS | GLAUKOS Corp | −749,422 | 482,219 | $51,915,697 | |
| MNDY | monday.com Ltd. | −679,949 | 13,370 | $924,000 | |
| RRX | Regal Rexnord Corp | −540,013 | 681,717 | $127,658,325 | |
| PCOR | Procore Technologies, Inc. | −539,012 | 1,001,253 | $57,071,421 | |
| CORZ | Core Scientific, Inc./tx | −512,722 | 1,480,013 | $22,140,994 | |
| SN | SharkNinja, Inc. | −497,756 | 904,541 | $95,790,891 | |
| BE | Bloom Energy Corp | −483,710 | 1,191,572 | $161,446,090 | |
| RMBS | Rambus Inc | −470,029 | 14,436 | $1,241,929 | |
| KRMN | Karman Holdings Inc. | −461,271 | 964,305 | $77,192,615 | |
| ASND | Ascendis Pharma A/S | −446,469 | 4,813,440 | $1,100,978,131 | |
| LEGN | Legend Biotech Corp | −331,011 | 5,763,475 | $104,261,262 | |
| VRT | Vertiv Holdings Co | −325,522 | 1,921,696 | $481,538,583 | |
| MTSI | MACOM Technology Solutions Holdings, Inc. | −304,039 | 132,457 | $29,414,725 | |
| NXT | Nextpower Inc. | −290,711 | 1,107,346 | $133,490,560 | |
| No positions match the current search. | |||||
New Positions
Positions the filer opened this quarter
25 positions
| Ticker | Company | Shares | Value | Open |
|---|---|---|---|---|
| APG | APi Group Corp | 4,634,929 | $187,807,323 | |
| ABVX | Abivax S.A. | 1,322,938 | $147,309,146 | |
| CELH | Celsius Holdings, Inc. | 3,768,911 | $133,720,962 | |
| LNG | Cheniere Energy, Inc. | 459,044 | $130,258,325 | |
| AS | Amer Sports, Inc. | 3,937,521 | $129,623,191 | |
| GH | Guardant Health, Inc. | 1,362,539 | $125,857,727 | |
| BROS | Dutch Bros Inc. | 2,313,357 | $117,194,665 | |
| AIG | American International Group, Inc. | 1,458,711 | $109,768,002 | |
| JLL | Jones Lang Lasalle Inc | 347,779 | $105,836,105 | |
| LGN | Legence Corp. | 1,861,653 | $105,108,928 | |
| ROST | Ross Stores, Inc. | 471,916 | $102,231,163 | |
| WWD | Woodward, Inc. | 272,185 | $97,420,455 | |
| ANET | Arista Networks, Inc. | 780,402 | $95,817,757 | |
| GRMN | Garmin Ltd | 376,362 | $87,319,747 | |
| LTH | Life Time Group Holdings, Inc. | 3,185,515 | $85,817,774 | |
| MS | Morgan Stanley | 496,558 | $81,718,550 | |
| MTZ | Mastec Inc | 249,980 | $80,428,565 | |
| ADPT | Adaptive Biotechnologies Corp | 5,436,718 | $75,461,645 | |
| GWRE | Guidewire Software, Inc. | 486,581 | $72,773,054 | |
| LOW | Lowes Companies Inc | 300,962 | $71,111,301 | |
| NAMS | NewAmsterdam Pharma Co N.V. | 2,202,913 | $70,515,245 | |
| PKG | Packaging Corp Of America | 303,771 | $64,466,281 | |
| MCHP | Microchip Technology Inc | 970,295 | $62,690,759 | |
| ZS | Zscaler, Inc. | 427,919 | $60,032,756 | |
| IBP | Installed Building Products, Inc. | 208,248 | $55,216,957 | |
| No positions match the current search. | ||||
Sold Out
Positions the filer fully exited
25 positions
| Ticker | Company | Shares | Value | Open |
|---|---|---|---|---|
| ORCL | Oracle Corp | 600,197 | $168,799,404 | |
| RBLX | Roblox Corp | 1,189,575 | $164,779,929 | |
| CVLT | Commvault Systems Inc | 786,175 | $148,414,116 | |
| IP | International Paper Co /New/ | 2,341,336 | $108,637,990 | |
| TRU | TransUnion | 1,180,154 | $98,873,302 | |
| COST | Costco Wholesale Corp /New | 92,163 | $85,308,837 | |
| AJG | Arthur J. Gallagher & Co. | 267,709 | $82,920,185 | |
| DKNG | DraftKings Inc. | 2,080,438 | $77,808,381 | |
| ALKT | Alkami Technology, Inc. | 3,095,058 | $76,881,240 | |
| ADMA | Adma Biologics, Inc. | 5,106,802 | $74,865,717 | |
| BLDR | Builders FirstSource, Inc. | 616,032 | $74,693,880 | |
| VMC | Vulcan Materials CO | 236,556 | $72,769,356 | |
| RYAN | Ryan Specialty Holdings, Inc. | 1,278,134 | $72,035,632 | |
| OWL | Blue Owl Capital Inc. | 4,228,444 | $71,587,556 | |
| PRI | Primerica, Inc. | 256,774 | $71,277,894 | |
| PRCT | PROCEPT BioRobotics Corp | 1,970,147 | $70,314,546 | |
| ICLR | Icon PLC | 396,354 | $69,361,950 | |
| RH | Rh | 332,901 | $67,632,167 | |
| PINS | Pinterest, Inc. | 2,023,270 | $65,088,595 | |
| VEEV | Veeva Systems Inc | 217,754 | $64,871,094 | |
| ICE | Intercontinental Exchange, Inc. | 378,565 | $63,780,631 | |
| SLNO | Soleno Therapeutics Inc | 899,157 | $60,783,013 | |
| KNSL | Kinsale Capital Group, Inc. | 142,146 | $60,449,007 | |
| TWLO | Twilio Inc | 591,367 | $59,189,923 | |
| SPOT | Spotify Technology S.A. | 84,006 | $58,636,188 | |
| No positions match the current search. | ||||
58 positions ·
$6,775,203,452 total
· Technology only
· as of Mar 31, 2026
All sectors
Basic Materials
Communication Services
Consumer Cyclical
Consumer Defensive
Energy
Financial Services
Healthcare
Industrials
Real Estate
Technology
Utilities
Showing 1–50
of 58 positions by value
· page 1 of 2
| Ticker | Company | Type | Shares | Value (USD) | % of Portfolio | History |
|---|---|---|---|---|---|---|
| NVDA |
Nvidia Corp
Technology
|
Reduced | 6,317,039 | $1,101,691,601 | 16.26% | |
| AAPL |
Apple Inc.
Technology
|
Reduced | 3,133,113 | $795,152,748 | 11.74% | |
| MSFT |
Microsoft Corp
Technology
|
Reduced | 1,649,513 | $610,600,227 | 9.01% | |
| AVGO |
Broadcom Inc.
Technology
|
Added | 1,236,925 | $382,840,656 | 5.65% | |
| MKSI |
Mks Inc
Technology
|
Added | 1,046,763 | $240,556,605 | 3.55% | |
| TSM |
Taiwan Semiconductor Manufacturing Co Ltd
Technology
|
Added | 493,504 | $166,779,676 | 2.46% | |
| MRVL |
Marvell Technology, Inc.
Technology
|
Reduced | 1,673,381 | $165,748,388 | 2.45% | |
| IOT |
Samsara Inc.
Technology
|
Added | 5,072,821 | $160,757,697 | 2.37% | |
| DT |
Dynatrace, Inc.
Technology
|
Added | 4,209,594 | $155,670,786 | 2.30% | |
| FN |
Fabrinet
Technology
|
Added | 284,874 | $148,567,488 | 2.19% | |
| NOW |
ServiceNow, Inc.
Technology
|
Added | 1,394,187 | $145,762,250 | 2.15% | |
| NXT |
Nextpower Inc.
Technology
|
Reduced | 1,107,346 | $133,490,560 | 1.97% | |
| NET |
Cloudflare, Inc.
Technology
|
Added | 541,566 | $111,746,728 | 1.65% | |
| P |
Everpure, Inc.
Technology
|
Added | 1,874,763 | $110,686,007 | 1.63% | |
| SNOW |
Snowflake Inc.
Technology
|
Added | 718,810 | $108,410,924 | 1.60% | |
| PANW |
Palo Alto Networks Inc
Technology
|
Added | 636,483 | $102,040,954 | 1.51% | |
| PLTR |
Palantir Technologies Inc.
Technology
|
Added | 674,557 | $98,674,197 | 1.46% | |
| SMTC |
Semtech Corp
Technology
|
Reduced | 1,280,594 | $98,464,872 | 1.45% | |
| ANET |
Arista Networks, Inc.
Technology
|
NEW | 780,402 | $95,817,757 | 1.41% | |
| COHR |
Coherent Corp.
Technology
|
Reduced | 396,644 | $94,484,567 | 1.39% | |
| ALAB |
Astera Labs, Inc.
Technology
|
Added | 860,113 | $94,268,384 | 1.39% | |
| BRZE |
Braze, Inc.
Technology
|
Added | 3,973,906 | $93,823,920 | 1.38% | |
| JBL |
Jabil Inc
Technology
|
Added | 349,209 | $92,760,386 | 1.37% | |
| GRMN |
Garmin Ltd
Technology
|
NEW | 376,362 | $87,319,747 | 1.29% | |
| CRDO |
Credo Technology Group Holding Ltd
Technology
|
Added | 926,219 | $86,944,177 | 1.28% | |
| FFIV |
F5, Inc.
Technology
|
Added | 298,542 | $86,377,156 | 1.27% | |
| PLXS |
Plexus Corp
Technology
|
Added | 384,493 | $77,875,212 | 1.15% | |
| CALX |
Calix, Inc
Technology
|
Added | 1,546,101 | $75,743,487 | 1.12% | |
| GWRE |
Guidewire Software, Inc.
Technology
|
NEW | 486,581 | $72,773,054 | 1.07% | |
| ONTO |
Onto Innovation Inc.
Technology
|
Reduced | 326,960 | $67,049,687 | 0.99% | |
| MCHP |
Microchip Technology Inc
Technology
|
NEW | 970,295 | $62,690,759 | 0.93% | |
| ZS |
Zscaler, Inc.
Technology
|
NEW | 427,919 | $60,032,756 | 0.89% | |
| DSGX |
Descartes Systems Group Inc
Technology
|
Reduced | 801,902 | $57,384,107 | 0.85% | |
| PCOR |
Procore Technologies, Inc.
Technology
|
Reduced | 1,001,253 | $57,071,421 | 0.84% | |
| HUBS |
Hubspot Inc
Technology
|
Added | 232,976 | $56,869,441 | 0.84% | |
| SNPS |
Synopsys Inc
Technology
|
Added | 132,848 | $52,671,575 | 0.78% | |
| LSCC |
Lattice Semiconductor Corp
Technology
|
Reduced | 563,422 | $52,263,024 | 0.77% | |
| CRM |
Salesforce, Inc.
Technology
|
NEW | 271,963 | $50,767,333 | 0.75% | |
| NXPI |
NXP Semiconductors N.V.
Technology
|
Added | 247,996 | $48,820,492 | 0.72% | |
| TOST |
Toast, Inc.
Technology
|
Added | 1,790,873 | $47,476,043 | 0.70% | |
| ENTG |
Entegris Inc
Technology
|
Reduced | 371,686 | $43,576,466 | 0.64% | |
| FICO |
Fair Isaac Corp
Technology
|
Added | 39,934 | $42,631,142 | 0.63% | |
| CPAY |
Corpay, Inc.
Technology
|
NEW | 143,120 | $41,646,488 | 0.61% | |
| MDB |
MongoDB, Inc.
Technology
|
Reduced | 164,881 | $40,357,922 | 0.60% | |
| IONQ |
IonQ, Inc.
Technology
|
Added | 1,373,788 | $39,606,308 | 0.58% | |
| MU |
Micron Technology Inc
Technology
|
NEW | 100,434 | $33,930,622 | 0.50% | |
| MTSI |
MACOM Technology Solutions Holdings, Inc.
Technology
|
Reduced | 132,457 | $29,414,725 | 0.43% | |
| RGTI |
Rigetti Computing, Inc.
Technology
|
NEW | 1,895,313 | $26,610,194 | 0.39% | |
| CORZ |
Core Scientific, Inc./tx
Technology
|
Reduced | 1,480,013 | $22,140,994 | 0.33% | |
| PTRN |
Pattern Group Inc.
Technology
|
Added | 1,172,891 | $14,579,035 | 0.22% |