Westfield Capital Management Co LP 13F Holdings
Westfield Capital Management Co LP's holdings from its Form 13F-HR filing for the quarter ended June 30, 2026, compared with the previous quarter (March 31, 2026). 13F filings list the long U.S. equity positions held by institutional investment managers with over $100 million under management.
Quarter
Q2 2026
Reported 13F value
$30.6B
Largest holding
Nvidia Corporation
Biggest Buys (Q2 2026)
| Security | Change | Value of change | % of portfolio |
|---|---|---|---|
| ASCENDIS PHARMA A/S | New position | $1.3B | 4.18% |
| ALPHABET INC (CAP STK CL A) | +1.72M sh | $555.4M | 4.38% |
| NVIDIA CORPORATION | +1.76M sh | $330.1M | 5.28% |
| AXON ENTERPRISE INC | +427,400 sh | $210.5M | 2.73% |
| SNOWFLAKE INC (COM SHS) | +1.02M sh | $206.2M | 1.44% |
| CARPENTER TECHNOLOGY CORP | New position | $193.7M | 0.63% |
| GILEAD SCIENCES INC | +1.26M sh | $167.5M | 0.53% |
| PTC THERAPEUTICS INC | New position | $159.6M | 0.52% |
| ADVANCED MICRO DEVICES INC | +398,100 sh | $156.1M | 0.76% |
| CATERPILLAR INC | +142,300 sh | $126.2M | 0.61% |
Biggest Sells (Q2 2026)
| Security | Change | Value of change | % of portfolio |
|---|---|---|---|
| ASCENDIS PHARMA A/S (SPONSORED ADR) | Sold out | -$1.1B | 0.00% |
| COMFORT SYS USA INC | -265,500 sh | -$446.1M | 2.30% |
| MARVELL TECHNOLOGY INC | -1.66M sh | -$329.5M | 0.01% |
| AMAZON COM INC | -1.42M sh | -$317.1M | 0.67% |
| BLOOM ENERGY CORP (COM CL A) | -1.18M sh | -$258.8M | 0.01% |
| VERTIV HOLDINGS CO (COM CL A) | -867,300 sh | -$253.9M | 1.15% |
| ASTERA LABS INC | -610,800 sh | -$181.0M | 0.39% |
| APPLE INC | -559,300 sh | -$151.9M | 2.43% |
| NETFLIX INC. | -1.68M sh | -$140.7M | 0.07% |
| REVOLUTION MEDICINES INC | -955,800 sh | -$136.0M | 0.37% |
Top 50 Holdings
| Security | Value | % of portfolio | Change in shares |
|---|---|---|---|
| NVIDIA CORPORATION | $1.6B | 5.28% | +27.91% |
| ALPHABET INC (CAP STK CL A) | $1.3B | 4.38% | +84.98% |
| ASCENDIS PHARMA A/S | $1.3B | 4.18% | New |
| AXON ENTERPRISE INC | $836.1M | 2.73% | +40.16% |
| FTAI AVIATION LTD | $794.6M | 2.60% | +3.12% |
| APPLE INC | $744.7M | 2.43% | -17.85% |
| COMFORT SYS USA INC | $704.5M | 2.30% | -42.76% |
| BROADCOM INC | $588.0M | 1.92% | +25.84% |
| MICROSOFT CORP | $527.6M | 1.72% | -14.26% |
| HOWMET AEROSPACE INC | $516.6M | 1.69% | -16.08% |
| ELI LILLY & CO | $499.8M | 1.63% | +14.30% |
| SNOWFLAKE INC (COM SHS) | $441.9M | 1.44% | +141.58% |
| MKS INC. | $413.0M | 1.35% | -11.29% |
| META PLATFORMS INC (CL A) | $381.6M | 1.25% | +28.58% |
| VERTIV HOLDINGS CO (COM CL A) | $353.0M | 1.15% | -45.13% |
| GE VERNOVA INC | $283.5M | 0.93% | +21.06% |
| MICRON TECHNOLOGY INC | $263.4M | 0.86% | +127.22% |
| VISA INC (COM CL A) | $261.6M | 0.85% | +66.99% |
| API GROUP CORP (COM STK) | $260.6M | 0.85% | +32.78% |
| TAPESTRY INC | $248.3M | 0.81% | -22.84% |
| RHYTHM PHARMACEUTICALS INC | $245.2M | 0.80% | +14.49% |
| LIFE TIME GROUP HOLDINGS INC | $244.8M | 0.80% | +88.20% |
| TAIWAN SEMICONDUCTOR MANUFAC (SPONSORED ADS) | $244.0M | 0.80% | +3.55% |
| GUARDANT HEALTH INC | $243.7M | 0.80% | +19.22% |
| QUANTA SVCS INC | $238.7M | 0.78% | -0.10% |
| SERVICENOW INC | $235.7M | 0.77% | +70.26% |
| ADVANCED MICRO DEVICES INC | $234.2M | 0.76% | +7929.50% |
| PALO ALTO NETWORKS INC | $224.5M | 0.73% | +3.43% |
| WOODWARD INC | $224.0M | 0.73% | +93.44% |
| ARISTA NETWORKS INC (COM SHS) | $223.7M | 0.73% | +68.77% |
| LPL FINL HLDGS INC | $223.4M | 0.73% | -10.03% |
| ROCKET LAB CORP | $214.9M | 0.70% | -33.37% |
| AMER SPORTS INC (COM SHS) | $214.7M | 0.70% | +61.14% |
| CLOUDFLARE INC (CL A COM) | $204.9M | 0.67% | +54.28% |
| AMAZON COM INC | $204.9M | 0.67% | -62.28% |
| GARMIN LTD | $204.5M | 0.67% | +128.78% |
| REGAL REXNORD CORPORATION | $204.1M | 0.67% | +25.71% |
| NATERA INC | $197.2M | 0.64% | -3.72% |
| MORGAN STANLEY (COM NEW) | $196.6M | 0.64% | +89.42% |
| CARPENTER TECHNOLOGY CORP | $193.7M | 0.63% | New |
| SAMSARA INC (COM CL A) | $189.3M | 0.62% | +15.05% |
| DYNATRACE INC (COM NEW) | $186.6M | 0.61% | +0.94% |
| CATERPILLAR INC | $186.0M | 0.61% | +440.20% |
| SEMTECH CORP | $183.4M | 0.60% | -11.50% |
| AMETEK INC | $175.1M | 0.57% | -2.95% |
| ABIVAX SA (SPONSORED ADS) | $174.5M | 0.57% | -0.99% |
| INSMED INC (COM PAR $.01) | $173.7M | 0.57% | +10.97% |
| ITT INC | $164.2M | 0.54% | +18.07% |
| GILEAD SCIENCES INC | $162.7M | 0.53% | +4724.39% |
| PTC THERAPEUTICS INC | $159.6M | 0.52% | New |
Values are as reported in the filing, adjusted for stock splits. Ranked by market value; options and other non-equity positions may be included where the filing lists them.
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