William Blair Investment Management, LLC

• A percentage of assets under your management
• Performance-based fees

Item 5.E lists how the firm is compensated for its advice; Items 5.B, 6.A, and 7.A show whether its people or related companies can also earn commissions. Percentage of assets, fixed, hourly, subscription, and performance-based fees come from clients (a performance-based fee depends on investment results); commissions come with a sale or a trade, often from the company behind the product. How fees, commissions, and other arrangements differ

The brochure lists different fees for different services or strategies. See the firm's brochure (dated March 31, 2026) for its fees and any account minimum, on the SEC's IAPD site.

$65,596,131,787 as of October 2026, filing dated April 9, 2026.

A measure of scale, not skill or returns. Discretionary means the firm decides trades; non-discretionary means clients approve each one. What assets under management means

A firm with no individual clients is an institutional manager even if it manages billions; the mix tells you whom the practice is built around.

• Portfolio management for individuals and/or small businesses
• Portfolio management for investment companies (and business development companies)
• Portfolio management for pooled investment vehicles (other than investment companies)
• Portfolio management for businesses (other than small businesses) or institutional clients

Registration

SEC-registered investment adviser. Status as filed: Approved.

Registered since

2014 (11 years)

Employees

Total: 388. Performing investment advisory functions: 142.

Wrap fee program participation

Yes.

Custodians (Schedule D, Section 5.K(3))

Bank of New York MellonState Street Bank and Trust CompanyThe Northern Trust Company

Custodians holding 10% or more of the firm's separately managed account assets, as filed on Form ADV (Schedule D, Section 5.K(3)). A custodian holds client assets; it does not endorse or supervise the firm. AdvisorCensus has no relationship with any custodian.

Other offices (Schedule D, Section 1.F)

3 other offices, as of the May 2026 filing

Baltimore, MDBoston, MANew York, NY

States registered or notice-filed

53 states or jurisdictions

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SEC-registered investment advisers are examined by the SEC. SEC, state, and exempt registration

3 Reports 3 disclosure items on Form ADV Item 11. View on IAPD.

Questions answered yes on this filing

Regulatory matters Items 11.C to 11.G

• 11.C(2) Has the SEC or the CFTC ever found that the firm or an advisory affiliate was involved in a violation of SEC or CFTC regulations or statutes?
• 11.C(4) Has the SEC or the CFTC ever entered an order against the firm or an advisory affiliate in connection with investment-related activity?
• 11.C(5) Has the SEC or the CFTC ever imposed a civil money penalty on the firm or an advisory affiliate, or ordered the firm or an advisory affiliate to cease and desist from an activity?

Each question covers the firm and its advisory affiliates: its current employees other than clerical staff, its officers, partners, and directors, and anyone who controls the firm or is controlled by it. One event can produce yes answers to several questions. SEC-registered advisers and exempt reporting advisers may leave out events more than ten years old, and may answer 11.A(2) and 11.B(2) for pending charges only. What happened, and who was involved, is on the Disclosure Reporting Pages of the IAPD record. Reading a firm's disclosures

Regulatory assets under management: $69,739,613,957 in the October 2021 data and $65,596,131,787 in the October 2026 data, down 6%.

Total employees: 345 in October 2021 and 388 in October 2026.

As filed in each year's data for the same month. Assets under management move with markets as well as with clients coming and going; they measure scale, not skill or returns. Most firms update these figures once a year.

1. April 2026
   • Employees performing advisory functions went from 152 to 142.
2. March 2026
   • Updated its list of owners and control persons (Schedule A).
3. February 2026
   • Updated its list of owners and control persons (Schedule A).

Compared month to month from the SEC's monthly adviser data and the state compilation feed. Owners and control persons are summarized, never named.