WESTFIELD CAPITAL MANAGEMENT CO LP
Institutional investor · Portfolio as of Q1 2026
Top Holdings250 positions
NVIDIA CORPORATION | 6.3M | $1.1B | 4.6% | $53.69 | +224.08% | 26 qtrssince 2019-Q4 | Increased 62 |
ASCENDIS PHARMA A/S | 4.8M | $1.1B | 4.6% | $119.23 | +104.11% | 30 qtrssince 2018-Q4 | Decreased 0 |
COMFORT SYS USA INC | 620,915 | $856.2M | 3.6% | $302.63 | +355.26% | 10 qtrssince 2023-Q4 | Decreased 0 |
APPLE INC | 3.1M | $795.2M | 3.3% | $95.33 | +165.75% | 30 qtrssince 2018-Q4 | Decreased 0 |
Ftai Aviation Ltd | 2.8M | $697.8M | 2.9% | $153.48 | +59.00% | 8 qtrssince 2024-Q2 | Increased 65 |
MICROSOFT CORP | 1.6M | $610.6M | 2.6% | $213.02 | +73.07% | 30 qtrssince 2018-Q4 | Increased 55 |
ALPHABET INC | 2M | $582.8M | 2.4% | $79.24 | +262.45% | 30 qtrssince 2018-Q4 | Decreased 0 |
HOWMET AEROSPACE INC | 2.3M | $527.7M | 2.2% | $161.25 | +42.79% | 5 qtrssince 2025-Q1 | Increased 56 |
VERTIV HOLDINGS CO | 1.9M | $481.5M | 2.0% | $70.30 | +256.29% | 11 qtrssince 2023-Q3 | Decreased 0 |
AMAZON COM INC | 2.3M | $474.8M | 2.0% | $123.79 | +68.24% | 30 qtrssince 2018-Q4 | Decreased 0 |
AXON ENTERPRISE INC | 1.1M | $451.9M | 1.9% | $361.64 | +17.43% | 14 qtrssince 2022-Q4 | Increased 61 |
BROADCOM INC | 1.2M | $382.8M | 1.6% | $172.69 | +78.62% | 30 qtrssince 2018-Q4 | Increased 55 |
ELI LILLY & CO | 364,579 | $335.3M | 1.4% | $779.42 | +17.64% | 16 qtrssince 2022-Q2 | Increased 62 |
TAPESTRY INC | 2.2M | $310.3M | 1.3% | $55.90 | +150.74% | 21 qtrssince 2021-Q1 | Increased 51 |
META PLATFORMS INC | 526,822 | $301.4M | 1.3% | $308.16 | +85.34% | 13 qtrssince 2023-Q1 | Decreased 0 |
LPL FINL HLDGS INC | 881,506 | $265.2M | 1.1% | $237.64 | +26.36% | 30 qtrssince 2018-Q4 | Increased 65 |
MKS INC. | 1M | $240.6M | 1.0% | $162.07 | +41.56% | 3 qtrssince 2025-Q3 | Increased 59 |
INSMED INC | 1.5M | $240.1M | 1.0% | $136.61 | +19.70% | 7 qtrssince 2024-Q3 | Increased 78 |
VAXCYTE INC | 3.6M | $211.9M | 0.9% | $52.80 | +13.29% | 11 qtrssince 2023-Q3 | Increased 44 |
ROCKET LAB CORP | 3.2M | $203.7M | 0.9% | $42.91 | +49.67% | 4 qtrssince 2025-Q2 | Increased 52 |
WESTFIELD CAPITAL MANAGEMENT CO LP manages $23.8B across 250 positions as of Q1 2026. Top holdings: NVDA (4.6%), ASND (4.6%), FIX (3.6%). Fund DNA: Balanced Allocator. HoldingsIntel Score: 2/5.0.
Active quarter - 46 new positions, 37 exits, 118 increased. Top move: INSM (INCREASED, conviction 78). Portfolio: $23.8B across 250 positions.
Top holdings by portfolio weight
Portfolio allocation by GICS sector
Behavioral investing profile
Position Outcomes
Best and worst performing positions by estimated return
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Cost basis estimates based on full filing history using quarter-end prices. Actual transaction prices are not disclosed in 13F filings.
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Data sourced from SEC EDGAR 13F filings. Not financial advice. Full disclaimer
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