# Westfield Capital Management

Westfield Capital Management is an Asset Manager based in Boston, United States.

## Overview

- **Organization type:** Asset Manager
- **Headquarters:** Boston, United States
- **Region:** North America
- **Address:** Boston, MA, United States
- **Founded:** 1989
- **Assets under management:** Undisclosed
- **Website:** westfieldcapital.com
- **LinkedIn:** https://www.linkedin.com/company/westfield-capital-management

## Regulatory record

- **CRD number:** 146990
- **SEC file number:** 801-69413
- **Registration status:** APPROVED
- **Latest Form ADV filing:** 2026-03-11T05:00:00.000Z
- **Reports private funds:** Yes
- **Private funds reported:** 0
- **IAPD record:** https://adviserinfo.sec.gov/firm/summary/146990

## About

Westfield Capital Management is an employee-owned investment firm specializing in U.S. growth equities with a disciplined, team-based approach. For over 35 years it has specialized in U.S. growth equities, leveraging deep industry expertise and rigorous research to build high-conviction, actively managed investment portfolios. Its growth equity strategies span the full market capitalization spectrum.

## Sectors

- Growth Equity
- Small Cap
- Small/Mid Cap
- Mid Cap
- Large Cap
- All Cap Select
- Growth
- Sector Focus
- Dividend Growth
- Health Care
- Sustainable Growth

## People

- William F. Muggia — President, CEO & CIO

## Questions

### Who runs investment decisions at Westfield Capital Management?

William F. Muggia serves as President, CEO, and Chief Investment Officer, a role he has held since founding the firm in 1989. He oversees all portfolio management and research activities. The investment committee structure, if any formal committee beyond Muggia exists, is not detailed in the firm's limited public disclosures.

### How does Westfield source investment ideas and construct portfolios?

Westfield employs a bottom-up, fundamental research process to identify companies exhibiting durable earnings growth, expanding margins, and sustainable competitive positions. Analysts conduct direct company and industry research; macroeconomic views influence sector weightings only at the margin. Portfolio concentration and high active share distinguish its approach from passive or core-allocation strategies.

### Does Westfield Capital Management participate in co-investments or private deals?

No. Westfield is a long-only public equity manager and does not engage in co-investments, direct private deals, or venture-stage funding. Its mandate is restricted to publicly traded US securities, a posture consistent since the firm's 1989 founding.

### What is Westfield's known posture on co-investments alongside external GPs?

Westfield does not participate in co-investment programs or club deals alongside external general partners. Its model is restricted to direct, long-only public equity investing through separately managed accounts and commingled funds, with no disclosed history of alternative or partnership-based co-invest structures.

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Last updated: 2026-08-11T15:08:32.892Z

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