William Blair & Company L.L.C.

Registered investment adviser · Chicago, IL · CRD #1252

Form ADV data as of 2026-09-01

Regulatory assets

$64.28 billion

Total accounts

39,781

Employees

492

Disclosure events

Firm details

Website: https://www.williamblair.com
Telephone: 312-236-1600
SEC file number: 801-688
Most recent Form ADV filing: 2026-03-31
SEC record: View this firm on the SEC's IAPD site

Disciplinary disclosures

This firm reports 6 disclosure questions answered Yes, covering 21 reported events. Form ADV Item 11 covers charges and pending proceedings as well as findings, so a Yes answer is not itself a finding of wrongdoing. The underlying detail is filed with the SEC.

SEC or CFTC found a false statement or omission
SEC or CFTC found a violation of its regulations or statutes
SEC or CFTC entered an order in connection with investment-related activity
SEC or CFTC imposed a civil money penalty or a cease-and-desist order
Another regulator found a violation of investment-related regulations or statutes
A self-regulatory organization found a violation of its rules

Assets and accounts

Provides continuous and regular supervisory or management services	Yes
Discretionary regulatory assets under management	$58.08 billion
Non-discretionary regulatory assets under management	$6.21 billion
Total regulatory assets under management	$64.28 billion
Discretionary accounts	38,800
Non-discretionary accounts	981
Total accounts	39,781
Regulatory assets under management attributable to non-U.S. persons	$214.9 million

People

Total employees (excluding clerical)	492
Employees performing investment advisory functions (including research)	231
Employees who are registered representatives of a broker-dealer	410
Employees registered as investment adviser representatives with a state	272
Employees registered as IARs for another investment adviser	0
Employees who are licensed insurance agents	49
Firms or persons who solicit advisory clients on the firm's behalf	4

Custody

Has custody of client cash or bank accounts	No
Has custody of client securities	Yes
Client funds and securities held in the firm's custody	$55.0 million
Clients for whom the firm has custody	12
A related person has custody of client cash or bank accounts	No
A related person has custody of client securities	No
The firm acts as a qualified custodian	No
A related person acts as a qualified custodian	No
Number of persons acting as qualified custodians for the firm's clients	1

How the firm is compensated

A percentage of assets under managementFixed fees (other than subscription fees)

Advisory services offered

Financial planning servicesPortfolio management for individuals and/or small businessesPortfolio management for pooled investment vehiclesPortfolio management for businesses or institutional clientsSelection of other advisers (including private fund managers)Other

Other business activities

Broker-dealer (registered or unregistered)Insurance broker or agent

Affiliated related persons

Broker-dealer, municipal securities dealer, or government securities broker or dealerOther investment adviser (including financial planners)Commodity pool operator or commodity trading advisorSponsor, general partner, or managing member of pooled investment vehicles

Reported conflicts of interest

Form ADV Items 8 asks advisers to disclose arrangements that may create a conflict with client interests. This firm answered Yes to:

Buys securities from or sells securities to advisory clients (principal transactions)
Buys or sells for itself securities it also recommends to clients
Recommends securities in which it has another proprietary interest
Executes agency cross transactions involving advisory client securities
Recommends securities for which it serves as underwriter or general partner
Recommends securities in which it has another sales interest
Recommends brokers or dealers to clients
Receives soft dollar benefits
Compensates a non-employee for client referrals
Provides employee compensation specifically for obtaining clients
Receives compensation from others for client referrals

Client types

Type of client	Clients	Assets
Individuals (other than high net worth individuals)	26,242	$7.33 billion
High net worth individuals	9,054	$45.35 billion
Pooled investment vehicles (other than investment companies and BDCs)	1	$5.6 million
Pension and profit sharing plans (not the participants or government plans)	364	$379.1 million
Charitable organizations	31	$1.77 billion
Other investment advisers	1,146	$1.39 billion
Corporations or other businesses not listed above	1,333	$8.06 billion