WESTFIELD CAPITAL MANAGEMENT CO LPWESTFIELD CAPITAL MANAGEMENT CO LP

Institutional investor · Portfolio as of Q1 2026

SEC EDGAR SourceSEC Filings

Top Holdings250 positions

Activity:
Stock
Shares
Value
Weight
Avg Buy
Est. P&L
Held
Conviction

NVIDIA CORPORATION

6.3M$1.1B4.6%$120.45+75.14%
26 qtrssince 2019-Q4
Increased
62
ASNDASND
ADR

ASCENDIS PHARMA A/S

4.8M$1.1B4.6%$119.23+126.82%
30 qtrssince 2018-Q4
Decreased
0

COMFORT SYS USA INC

620,915$856.2M3.6%$304.00+477.67%
10 qtrssince 2023-Q4
Decreased
0

APPLE INC

3.1M$795.2M3.3%$127.67+146.97%
30 qtrssince 2018-Q4
Decreased
0

FTAI AVIATION LTD

2.8M$697.8M2.9%$155.99+45.74%
8 qtrssince 2024-Q2
Increased
65

MICROSOFT CORP

1.6M$610.6M2.6%$214.46+79.57%
30 qtrssince 2018-Q4
Increased
55

ALPHABET INC

2M$582.8M2.4%$109.55+226.05%
30 qtrssince 2018-Q4
Decreased
0

HOWMET AEROSPACE INC

2.3M$527.7M2.2%$161.91+67.28%
5 qtrssince 2025-Q1
Increased
56

VERTIV HOLDINGS CO

1.9M$481.5M2.0%$70.31+353.51%
11 qtrssince 2023-Q3
Decreased
0

AMAZON COM INC

2.3M$474.8M2.0%$137.14+78.90%
30 qtrssince 2018-Q4
Decreased
0

AXON ENTERPRISE INC

1.1M$451.9M1.9%$397.09+42.49%
14 qtrssince 2022-Q4
Increased
61

BROADCOM INC

1.2M$382.8M1.6%$190.46+110.00%
30 qtrssince 2018-Q4
Increased
55

ELI LILLY & CO

364,579$335.3M1.4%$803.24+47.97%
16 qtrssince 2022-Q2
Increased
62

TAPESTRY INC

2.2M$310.3M1.3%$57.23+145.92%
21 qtrssince 2021-Q1
Increased
51

META PLATFORMS INC

526,822$301.4M1.3%$305.10+119.34%
13 qtrssince 2023-Q1
Decreased
0

LPL FINL HLDGS INC

881,506$265.2M1.1%$240.73+31.70%
30 qtrssince 2018-Q4
Increased
65

MKS INC.

1M$240.6M1.0%$163.49+125.44%
3 qtrssince 2025-Q3
Increased
59

INSMED INC

1.5M$240.1M1.0%$125.07-7.57%
7 qtrssince 2024-Q3
Increased
78

VAXCYTE INC

3.6M$211.9M0.9%$52.80+10.25%
11 qtrssince 2023-Q3
Increased
44

ROCKET LAB CORP

3.2M$203.7M0.9%$43.71+85.40%
4 qtrssince 2025-Q2
Increased
52
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$23.8B
AUM
250
Positions
Q1 2026
Filing
Rating · 3.0
Quarterly Portfolio Change
+4%Q4'24$23B-11%Q1'25$20.5B+16%Q2'25$23.8B-0%Q3'25$23.8B+1%Q4'25$24B-1%Q1'26$23.8B
Activity profile
$ moved · Q1'26
New20%Increased30%Decreased33%Exited17%
Composition
Equity vs derivatives
Equity100%Puts0%Calls0%
Holding period
Avg 3.6 years
<1Q10%1-4Q18%1-2Y12%2Y+60%

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.

Q1 2026 Summary

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

Total AUM$24B
NVDA4.62%
ASND4.62%
FIX3.59%
AAPL3.34%
FTAI2.93%
MSFT2.56%
GOOGL2.45%
HWM2.21%
VRT2.02%
AMZN1.99%
Other1.90%

Portfolio allocation by GICS sector

Sectors11
Technology28.43%
Industrials25.27%
Healthcare15.80%
Consumer Cyclical10.50%
Financial Services8.86%
Communication Services5.93%
Energy2.69%
Consumer Defensive0.91%
Basic Materials0.61%
Utilities0.54%
Other0.47%

Behavioral investing profile

7-dimension quality assessment
Solid(3.0 / 5.0)
Track Record65
Conviction43
Concentration46
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Position Outcomes

Best and worst performing positions by estimated return

Cost basis estimates based on full filing history using quarter-end prices. Actual transaction prices are not disclosed in 13F filings.

Accumulation Streaks

Positions with 2+ consecutive quarters of increases - persistent directional conviction.

Security
7Q
DTDYNATRACE INC
Q3 2024 Q1 2026+2.2M shares+$63.7M
6Q
AITAPPLIED INDL TECHNOLOGIES IN
Q4 2024 Q1 2026+144,744 shares+$44.5M
4Q
BRZEBRAZE INC
Q2 2025 Q1 2026+2.5M shares+$39.2M

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Data sourced from SEC EDGAR 13F filings. Not financial advice. Full disclaimer

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