Asset manager · Boston, MA
Westfield Capital Management Company, L.P.
SEC-registered investment adviser · CRD 146990 · SEC 801-69413
At a glance
Westfield Capital Management Company, L.P. is an SEC-registered investment adviser based in Boston, Massachusetts, with $29.8 billion in regulatory assets under management as of its Form ADV filed July 1, 2026. Its largest client group by assets is investment companies, and it reports 8,910 individual clients. By Form ADV it is a asset manager, ranked 296th of 3,218 asset managers and 659th of 17,210 SEC-registered advisers by assets.
Main office 617-428-7100westfieldcapital.comLinkedInAs filed on Form ADV
- Regulatory AUM
- $30B
- Rank among asset managers
- #296 of 3,218
- Rank among all SEC RIAs
- #659 of 17,210
- Rank in Massachusetts
- #51 of 627
- Individual clients
- 8,910
- High-net-worth clients
- 512
- Accounts
- 9,391
- Discretionary
- 100% of AUM
- Employees
- 63
- Advisory staff
- 19
- Offices
- 1
Owners and executives on its Form ADV
- William A. MuggiaChief Executive Officer and Chief Investment Officer
- Kathryn A. KearneyPartner, Chief Financial Officer and Chief Compliance Officer
- John M. MontgomeryChief Operating Officer
- Richard D. LeeChief Investment Officer
Custody and brokerage
Who it serves
| Client type | Clients | Regulatory AUM | Share |
|---|---|---|---|
| Investment companies | 15 | $10.0B | 34% |
| Pension and profit sharing plans | 177 | $6.4B | 21% |
| Pooled investment vehicles | 15 | $4.5B | 15% |
| State or municipal government entities | 38 | $4.3B | 14% |
| Charitable organizations | 138 | $1.4B | 5% |
| High-net-worth individuals | 512 | $1.3B | 4% |
| Individuals | 8,398 | $699M | 2% |
| Other investment advisers | 1 | $661M | 2% |
| Corporations or other businesses | 97 | $496M | 2% |
Private funds
Westfield Capital Management Company, L.P. reports 2 private funds with $71M in gross assets: hedge funds, other private funds (Form ADV Item 7.B).
Disciplinary disclosures
Westfield Capital Management Company, L.P. reports no disciplinary disclosures in Item 11 of Form ADV. Read the details on the SEC’s adviser search ↗
Services
- Portfolio management for individuals and small businesses
- Portfolio management for investment companies
- Portfolio management for pooled investment vehicles
- Portfolio management for businesses and institutions
How it’s paid
- A percentage of assets under management
- Performance-based fees
Form ADV and brochures on the SEC’s adviser search ↗westfieldcapital.com ↗
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Ten years of SEC filings, its owners and contacts, and how it stacks up against its peers. Atlas members see all of it.
- Assets, accounts, clients and staff, ten years of filings
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- Rank against 375 peers of its type and size
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- Filing changes this year, with alerts
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Background
Questions
How much does Westfield Capital Management Company, L.P. manage?
Westfield Capital Management Company, L.P. reports $29.8 billion in regulatory assets under management across 9,391 accounts, 100% of it on a discretionary basis, on its Form ADV filed July 1, 2026.
What kind of firm is Westfield Capital Management Company, L.P.?
Westfield Capital Management Company, L.P. is a asset manager by its Form ADV answers. Most of its assets are managed for funds, institutions or other businesses rather than individuals.
Who are Westfield Capital Management Company, L.P.’s clients?
By assets, its largest client types are investment companies ($10.0 billion, 15 clients); pension and profit sharing plans ($6.4 billion, 177 clients); pooled investment vehicles ($4.5 billion, 15 clients).
Does Westfield Capital Management Company, L.P. manage private funds?
Yes. It reports 2 private funds with $71 million in gross assets, including hedge funds, other private funds.
Does Westfield Capital Management Company, L.P. have any disciplinary history?
Westfield Capital Management Company, L.P. reports no disciplinary disclosures in Item 11 of its Form ADV. Check the SEC’s adviser search for the latest record.
Where these numbers come from
Every figure is Westfield Capital Management Company, L.P.’s own answer on its latest Form ADV, from the SEC’s registered-adviser list as of October 1, 2026: regulatory assets and accounts (Item 5.F), clients by type (5.D), employees (5.A and 5.B), compensation (5.E) and services (5.G). Custodians come from Schedule D 5.K(3) of its latest filing (2026-07-01), which lists those holding 10% or more of separately managed account assets and the amount at each. “Hybrid” means some employees are also registered representatives of a broker-dealer (Item 5.B(2)); affiliated broker-dealers are the related persons it lists in Item 7.A and Schedule D. Firm type comes from its own answers: broker-dealer firms are registered broker-dealers themselves (Item 6.A); private fund advisers manage mostly private funds (Item 7.B, 5.D); wealth managers manage at least half their assets for individuals (5.D). Ranks compare it by regulatory assets with every SEC-registered adviser and with firms of its type. Figures are as of the firm’s last annual update, so they can lag recent deals and market moves. Regulatory AUM counts assets the firm continuously supervises and can differ from what a firm markets.
Not an endorsement or a recommendation. Before hiring any adviser, read its Form ADV Part 2A brochure and check its record on the SEC’s adviser search. How to check a financial advisor →