WESTFIELD CAPITAL MANAGEMENT CO LP
Q4 2021 Form 13-F

BOSTON, MASSACHUSETTS
CIK 0001177719 · CRD 146990 · SEC-registered investment adviser
$16.8B Reported Value Total

WESTFIELD CAPITAL MANAGEMENT COMPANY, L.P. reports 756 total accounts under management (AUM). There are 756 discretionary accounts valued at $17,023,240,581, 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
$16.8B
Quarter over quarter
+6.9%
Holdings
244
Top-10 concentration
24.0%

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
Q3 2021
Q1 2022
Go to latest

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

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Q4 2021 13F filing summary

Period of report December 31, 2021
Filed February 10, 2022
Form 13F-HR
Reported value $16.8B
Positions 244
Change in reported value +1.5%
New positions 42
Exited positions 33
Position turnover 27.1%
Top-10 concentration 24.0%

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 · Q4 2021

# Holding Reported value % of portfolio
1 AAPL APPLE INC $741.3M 4.41%
2 MSFT MICROSOFT CORP $533.8M 3.17%
3 GOOGL ALPHABET INC $531.3M 3.16%
4 AMZN AMAZON COM INC $460.6M 2.74%
5 ICLR ICON PLC $388.5M 2.31%
6 ASND ASCENDIS PHARMA A/S $355.3M 2.11%
7 META META PLATFORMS INC $317.2M 1.89%
8 BIO BIO RAD LABS INC $250.6M 1.49%
9 FTNT FORTINET INC $230.3M 1.37%
10 TDG TRANSDIGM GROUP INC $230.2M 1.37%
11 NOW SERVICENOW INC $210.9M 1.25%
12 ATKR ATKORE INC $194.2M 1.15%
13 V VISA INC $190.2M 1.13%
14 CRM SALESFORCE COM INC $183.6M 1.09%
15 AME AMETEK INC $181.7M 1.08%
16 MGM MGM RESORTS INTERNATIONAL $177.1M 1.05%
17 ZEN ZENDESK INC $173.7M 1.03%
18 WMS ADVANCED DRAIN SYS INC DEL $173.1M 1.03%
19 WDAY WORKDAY INC $171.5M 1.02%
20 LPLA LPL FINL HLDGS INC $171.2M 1.02%

Values as reported on the Q4 2021 Form 13F. Every position is in the holdings table below.

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