WESTFIELD CAPITAL MANAGEMENT CO LP
Institutional investor · Portfolio as of Q1 2026
Top Holdings250 positions
Stock | Shares | Value | Weight | Avg Buy | Est. P&L | Held | Conviction |
|---|---|---|---|---|---|---|---|
NVIDIA CORP | 6.3M | $1.1B | 4.6% | $120.45 | +49.48% | 26 qtrssince 2019-Q4 | Increased 62 |
ASCENDIS PHARMA A/S | 4.8M | $1.1B | 4.6% | $119.23 | +107.49% | 30 qtrssince 2018-Q4 | Decreased 0 |
COMFORT SYSTEMS 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% | $128.39 | +97.32% | 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% | $214.46 | +88.35% | 30 qtrssince 2018-Q4 | Increased 55 |
ALPHABET INC-CL A | 2M | $582.8M | 2.4% | $109.55 | +177.12% | 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-A | 1.9M | $481.5M | 2.0% | $70.31 | +247.66% | 11 qtrssince 2023-Q3 | Decreased 0 |
AMAZON.COM INC | 2.3M | $474.8M | 2.0% | $137.14 | +52.20% | 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% | $188.78 | +63.69% | 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% | $57.23 | +169.84% | 21 qtrssince 2021-Q1 | Increased 51 |
META PLATFORMS INC-CLASS A | 526,822 | $301.4M | 1.3% | $305.10 | +114.71% | 13 qtrssince 2023-Q1 | Decreased 0 |
LPL FINANCIAL HOLDINGS INC | 881,506 | $265.2M | 1.1% | $237.64 | +26.36% | 30 qtrssince 2018-Q4 | Increased 65 |
MKS INC | 1M | $240.6M | 1.0% | $163.49 | +42.25% | 3 qtrssince 2025-Q3 | Increased 59 |
INSMED INC | 1.5M | $240.1M | 1.0% | $125.07 | +17.53% | 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% | $43.71 | +60.44% | 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 Rating: 3/5.0.
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
Top Winners
Top Losers
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