William Blair Investment Management: AUM & Ownership

Clients

William Blair Investment Management serves 682 clients, 386 of them other clients. The average client has about $96 million with the firm, and high-net-worth clients hold 0% of its $65.6 billion in assets.

Regulatory assets by client type

Investment companies29 clients24%
Pooled investment vehicles51 clients34%
Pension and profit-sharing plans73 clients18%
Charitable organizations68 clients4%
State or municipal government entities54 clients18%
OtherHigh-net-worth individuals, Other investment advisers, Insurance companies, Sovereign wealth funds and foreign official institutions, Corporations and other businesses, Other2%

Show client breakdown

Client type	Clients	Regulatory AUM	Share	Avg. per client
High-net-worth individuals	2	$18,307,395	0.0%	$9.15M
Investment companies	29	$15,843,070,677	24.2%	$546.3M
Pooled investment vehicles	51	$22,147,916,513	33.8%	$434.3M
Pension and profit-sharing plans	73	$11,851,584,002	18.1%	$162.4M
Charitable organizations	68	$2,337,130,386	3.6%	$34.4M
State or municipal government entities	54	$11,930,157,073	18.2%	$220.9M
Other investment advisers	1	$320,704,865	0.5%	$320.7M
Insurance companies	4	$23,539,301	0.0%	$5.88M
Sovereign wealth funds and foreign official institutions	4	$721,467,066	1.1%	$180.4M
Corporations and other businesses	10	$209,518,216	0.3%	$21.0M
Other	386	$192,736,293	0.3%	$499K
Total	682	$65,596,131,787	100%	$96.2M

High-net-worth individuals

Clients: 2
Regulatory AUM: $18,307,395
Share: 0.0%
Avg. per client: $9.15M

Investment companies

Clients: 29
Regulatory AUM: $15,843,070,677
Share: 24.2%
Avg. per client: $546.3M

Pooled investment vehicles

Clients: 51
Regulatory AUM: $22,147,916,513
Share: 33.8%
Avg. per client: $434.3M

Pension and profit-sharing plans

Clients: 73
Regulatory AUM: $11,851,584,002
Share: 18.1%
Avg. per client: $162.4M

Charitable organizations

Clients: 68
Regulatory AUM: $2,337,130,386
Share: 3.6%
Avg. per client: $34.4M

State or municipal government entities

Clients: 54
Regulatory AUM: $11,930,157,073
Share: 18.2%
Avg. per client: $220.9M

Other investment advisers

Clients: 1
Regulatory AUM: $320,704,865
Share: 0.5%
Avg. per client: $320.7M

Insurance companies

Clients: 4
Regulatory AUM: $23,539,301
Share: 0.0%
Avg. per client: $5.88M

Sovereign wealth funds and foreign official institutions

Clients: 4
Regulatory AUM: $721,467,066
Share: 1.1%
Avg. per client: $180.4M

Corporations and other businesses

Clients: 10
Regulatory AUM: $209,518,216
Share: 0.3%
Avg. per client: $21.0M

Other

Clients: 386
Regulatory AUM: $192,736,293
Share: 0.3%
Avg. per client: $499K

Total

Clients: 682
Regulatory AUM: $65,596,131,787
Share: 100%
Avg. per client: $96.2M

What it does

William Blair Investment Management provides portfolio management for individuals and small businesses, portfolio management for investment companies, portfolio management for pooled vehicles and portfolio management for institutions. It is paid through a percentage of assets and performance-based fees.

William Blair Investment Management advises 9 private funds.

100.0% of assets ($65.60B across 682 accounts) are managed with discretion. $192.7M sits in a wrap fee program the firm both sponsors and manages. 5% of clients are outside the U.S., and 18 clients received advice without assets under management last fiscal year.

What the accounts hold

Separately managed account assets by class, year end

Stocks95%
Funds4%
Other1%
- The total sum of the asset type percentages with less than one half percent asset is over one half percent. this was rounded up to 1% and entered in (xii) other.1%

Custodians

William Blair Investment Management’s client accounts are held mainly at The Northern Trust, with 14% of managed assets, and State Street Bank and Trust, with 12%. William Blair Investment Management has custody of $464.4M for 4 clients.

Managed account assets by custodian

Bank of New York MellonBank of New York Mellon · Chicago, IL · $6.19B9%
The Northern TrustThe Northern Trust Company · Chicago, IL · $9.05B14%
State Street Bank and TrustState Street Bank and Trust Company · Boston, MA · $7.72B12%
All other custodians$42.64B65%

Ownership and leadership

WBC Holdings, L.P. owns 75% or more of William Blair Investment Management, and Brent Walker Gledhill is its CEO.

Who owns the firm

William Blair Investment Management, LLC· the adviser

WBC Holdings, L.P.
Control person · since October 2014
Owns 75% or more of William Blair Investment Management, LLC
- WBC GP L.L.C.
  General partner · Control person · since October 2014

Leadership

Brent Walker Gledhill
President, Chief Executive Officer, Executive Committee Member
Michael William Trimberger
Chief Financial Officer, Executive Committee Member
Beth A Satterfield
Chief Operating Officer, Executive Committee Member
Telmo Martins
Chief Compliance Officer
Lisa Anderson
Director of Operations
Cissie Citardi
General Counsel, Executive Committee Member
Ryan Jacob Devore
Executive Committee Member
Robert Daniel Kendall
Global Head of Investment Management, Executive Committee Member
Scott Thomas McLaughlin
Executive Committee Member
Steven Robert Tole
Executive Committee Member
Matthew Montgomery Zimmer
Executive Committee Member

Staff

388 employees
142 in advisory functions
119 broker-dealer reps
4 soliciting firms

Reported holdings

William Blair Investment Management’s reported 13F holdings total $33.25B across 403 positions, and the ten largest make up 28.9% of it.

$33.25B
Reported 13F value: 403
Positions: 28.9%
In the 10 largest: +9.9%
Value vs. prior quarter

Ten largest positions, share of reported value

Taiwan Semiconductor Manufac · Sponsored ADS7.1%
Nvidia Corporation5.2%
Alphabet Inc. · Cap Stk CL A3.4%
Apple Inc.2.8%
Broadcom Inc.2.3%
Microsoft Corp.2.3%
Meta Platforms Inc. · CL A1.6%
Amazon Com Inc.1.4%
Mastercard Incorporated · CL A1.4%
Advanced Micro Devices Inc.1.3%

Together, the ten largest are 28.9% of reported value.

The 50 largest positions and quarterly changesQuarter ended 30 June 2026 · filed 12 August 2026

A 13F covers only exchange-traded long positions the firm holds with discretion, so this $33.25B is not its $65.60B in regulatory assets and does not represent any individual client's portfolio.

Fees

William Blair Investment Management is paid through a percentage of assets under management and performance-based fees.

William Blair Investment Management’s fee rates are not included in this profile. Find its brochure on the SEC’s site.

Offices and registrations

Besides its headquarters, William Blair Investment Management has 3 offices, with 4 listed addresses across 4 states.

Listed office addresses by state

Illinois · 1 listed address

150 North Riverside Plaza, ChicagoHQ

Registration details

Legal name: William Blair Investment Management, LLC
Headquarters: 150 North Riverside Plaza, Chicago, IL 60606-1598
Phone: 312-236-1600
Website: www.williamblair.com
SEC file: 801-80640
Structure: Delaware LLC
Fiscal year end: December

This directory does not report disciplinary history, for any firm or individual, in either direction. The SEC publishes the complete record, including any disciplinary events, and it is the authoritative place to check one. See this firm's record on adviserinfo.sec.gov

Common questions

How many clients does William Blair Investment Management have?

William Blair Investment Management has 682 clients and manages $65.6 billion for them, as of April 2026. They include 386 other clients, 73 pension and profit-sharing plans and 68 charitable organizations.

Source: Form ADV Part 1A, Items 5.D and 5.F, filed 9 April 2026

What services does William Blair Investment Management offer?

Source: Form ADV Part 1A, Item 5.G, from the SEC's 2 October 2026 data file

Which custodians does William Blair Investment Management use?

William Blair Investment Management’s separately managed account assets are held at The Northern Trust Company (Chicago, IL), with $9,045,075,301, State Street Bank and Trust Company (Boston, MA), with $7,721,321,009 and Bank of New York Mellon (Chicago, IL), with $6,189,911,537. Only custodians holding at least a tenth of those assets are named.

Source: Form ADV Part 1A, Schedule D, Section 5.K.(3), filed 9 April 2026

How many financial advisors does William Blair Investment Management have?

William Blair Investment Management has 0 investment adviser representatives registered with state securities authorities, out of 388 employees, and 142 perform investment advisory functions. 119 are registered representatives of a broker-dealer and 0 are licensed insurance agents.

Source: Form ADV Part 1A, Items 5.A and 5.B, from the SEC's 2 October 2026 data file

What does William Blair Investment Management invest in?

At the end of its last fiscal year, William Blair Investment Management’s separately managed accounts held 95% exchange-traded equities, 4% registered funds (mutual funds, ETFs, BDCs) and 1% the total sum of the asset type percentages with less than one half percent asset is over one half percent. this was rounded up to 1% and entered in (xii) other.. It advises 9 private funds.

Source: Form ADV Part 1A, Items 5.K.(1) and 7.B, from the SEC's 2 October 2026 data file

Who owns William Blair Investment Management?

William Blair Investment Management’s direct owner is WBC Holdings, L.P. (75% or more).

Source: Form ADV Part 1A, Schedules A and B, filed 9 April 2026

How does William Blair Investment Management get paid?

William Blair Investment Management is paid through a percentage of assets under management and performance-based fees. Its Form ADV lists no commissions among how it is paid.

Source: Form ADV Part 1A, Item 5.E, from the SEC's 2 October 2026 data file