WESTFIELD CAPITAL MANAGEMENT CO LP
Q2 2025 Form 13-F

BOSTON, MASSACHUSETTS
CIK 0001177719 · CRD 146990 · SEC-registered investment adviser
$23.8B Reported Value Total

WESTFIELD CAPITAL MANAGEMENT COMPANY, L.P. reports 975 total accounts under management (AUM). There are 975 discretionary accounts valued at $23,551,448,142, and 0 non-discretionary accounts.

Source: Form ADV filed * Note that certain holdings are exempt from Form 13-F reporting, so the AUM totals may be greater than the Form 13-F total.
SEC Registered Discretionary Manager
Firm Brochure (Part 2A) Client Relationship Summary (Form CRS)
Private funds (Form ADV)
11 funds · $185.4M gross asset value
Other: $68.8M · Hedge Fund: $34.8M · Private Equity Fund: $128.8K
Source: Form ADV filed 2026-07-01
Reported value
$23.8B
Quarter over quarter
+17.3%
Holdings
239
Top-10 concentration
29.7%

Filing Structure

Reports holdings for

Holdings reported by

Key People

Form ADV owners & control persons
William Albert Muggia
MEMBER OF MANAGEMENT COMMITTEE
Kathryn Ann Kearney
PARTNER, CHIEF FINANCIAL OFFICER AND CHIEF COMPLIANCE OFFICER
Richard Dailyong Lee
CHIEF INVESTMENT OFFICER
Q1 2025
Q3 2025
Go to latest

Coverage begins with the second quarter of 2013. Earlier quarters are not shown while their accuracy is being verified.

Loading 13F Metrics

Q2 2025 13F filing summary

Period of report June 30, 2025
Filed August 12, 2025
Form 13F-HR
Reported value $23.8B
Positions 239
Change in reported value +16.0%
New positions 39
Exited positions 44
Position turnover 29.3%
Top-10 concentration 29.7%

13F filings by quarter

Quarter Positions Value
Q2 2026 13F
Filed Aug 12, 2026
 278 $30.6B
Q1 2026 13F
Filed May 11, 2026
 250 $23.8B
Q4 2025 13F
Filed Feb 11, 2026
 241 $24.0B
Q3 2025 13F
Filed Nov 12, 2025
 235 $23.8B
Q2 2025 13F
Filed Aug 12, 2025
 239 $23.8B
Q1 2025 13F
Filed May 9, 2025
 244 $20.5B
Q4 2024 13F
Filed Feb 11, 2025
 239 $23.0B
Q3 2024 13F
Filed Nov 12, 2024
 247 $22.1B
Q2 2024 13F
Filed Aug 14, 2024
 248 $20.4B
Q1 2024 13F
Filed May 10, 2024
 244 $19.0B
Q4 2023 13F
Filed Feb 9, 2024
 239 $17.2B
Q3 2023 13F
Filed Nov 13, 2023
 234 $14.7B
Q2 2023 13F
Filed Aug 11, 2023
 227 $15.7B
Q1 2023 13F
Filed May 12, 2023
 222 $14.2B
Q4 2022 13F
Filed Feb 13, 2023
 226 $13.0B
Q3 2022 13F
Filed Nov 14, 2022
 230 $12.6B
Q2 2022 13F
Filed Aug 12, 2022
 235 $12.7B
Q1 2022 13F
Filed May 16, 2022
 235 $15.6B
Q4 2021 13F
Filed Feb 10, 2022
 244 $16.8B
Q3 2021 13F
Filed Nov 12, 2021
 235 $16.6B

33 earlier quarters on file — choose one from the quarter menu above.

Top 20 holdings · Q2 2025

# Holding Reported value % of portfolio
1 NVDA NVIDIA CORPORATION $1.2B 5.0%
2 ASND ASCENDIS PHARMA A/S $940.9M 3.95%
3 MSFT MICROSOFT CORP $874.2M 3.67%
4 AAPL APPLE INC $716.9M 3.01%
5 AMZN AMAZON COM INC $680.2M 2.85%
6 AXON AXON ENTERPRISE INC $654.1M 2.74%
7 META META PLATFORMS INC $633.6M 2.66%
8 FIX COMFORT SYS USA INC $502.1M 2.11%
9 GOOGL ALPHABET INC $453.2M 1.9%
10 TDG TRANSDIGM GROUP INC $441.0M 1.85%
11 AVGO BROADCOM INC $368.3M 1.54%
12 HWM HOWMET AEROSPACE INC $356.6M 1.5%
13 VRT VERTIV HOLDINGS CO $338.7M 1.42%
14 NFLX NETFLIX INC $337.4M 1.41%
15 NOW SERVICENOW INC $306.7M 1.29%
16 TPR TAPESTRY INC $300.2M 1.26%
17 LPLA LPL FINL HLDGS INC $293.3M 1.23%
18 V VISA INC $282.8M 1.19%
19 LLY ELI LILLY & CO $239.7M 1.01%
20 LEGN LEGEND BIOTECH CORP $229.7M 0.96%

Values as reported on the Q2 2025 Form 13F. Every position is in the holdings table below.

Loading Activities
Loading Sector Allocation
Crunching numbers
Loading Performance
Finding Potential New Buys
Building table
Loading SEC filing data
Loading Form 4 Filings
Loading 13D/G filings