# William Blair Investment Management, LLC

> William Blair Investment Management, LLC is an SEC-registered investment advisory firm in Chicago, IL, registered since 2014, reporting over $5 billion in regulatory assets under management in its Form ADV filing dated April 9, 2026.

- CRD: 173961
- Filed as: WILLIAM BLAIR INVESTMENT MANAGEMENT, LLC
- Registration: SEC-registered investment adviser (status as filed: Approved)
- Location: Chicago, IL
- Filing period: October 2026
- Form ADV filing dated: April 9, 2026
- SEC record (IAPD): https://adviserinfo.sec.gov/firm/summary/173961
- AdvisorCensus page: https://advisorcensus.com/firm/william-blair-investment-management-llc-chicago-il-173961

## Quick answers

**How is William Blair Investment Management, LLC compensated?**
On its Form ADV (Item 5.E, October 2026), William Blair Investment Management, LLC reports these compensation arrangements: a percentage of assets under its management; performance-based fees. The amounts are in Item 5 of its Form ADV Part 2A brochure.

**Where is William Blair Investment Management, LLC located?**
William Blair Investment Management, LLC's principal office is in Chicago, IL, according to its Form ADV; the May 2026 filing also lists 3 other offices (Schedule D, Section 1.F).

**Is William Blair Investment Management, LLC registered with the SEC or a state?**
William Blair Investment Management, LLC is an SEC-registered investment advisory firm, registered since 2014. Status as filed: Approved. CRD 173961.

**How much does William Blair Investment Management, LLC manage?**
William Blair Investment Management, LLC reports $65,596,131,787 in regulatory assets under management in its Form ADV filing dated April 9, 2026 (100% discretionary).

**How have William Blair Investment Management, LLC's assets and staff changed since 2021?**
In the Form ADV data for William Blair Investment Management, LLC: 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. Assets under management move with markets as well as with clients coming and going.

**What types of clients does William Blair Investment Management, LLC serve?**
By number of clients on Form ADV Item 5.D: other (386); pension and profit sharing plans (but not the plan participants or government pension plans) (73); charitable organizations (68).

**Which custodians does William Blair Investment Management, LLC use?**
William Blair Investment Management, LLC's most recent Form ADV filing (Schedule D, Section 5.K(3)) lists Bank of New York Mellon, State Street Bank and Trust Company and The Northern Trust Company as custodians holding 10% or more of its separately managed account assets.

**Does William Blair Investment Management, LLC report any disciplinary disclosures?**
Reports 3 disclosure items on Form ADV Item 11: yes answers to 11.C(2) (SEC or CFTC finding of a violation), 11.C(4) (SEC or CFTC order), and 11.C(5) (SEC or CFTC civil money penalty or cease-and-desist order). Each question covers the firm and its advisory affiliates, and one event can produce several yes answers. The detail of any item is on the firm's SEC record: https://adviserinfo.sec.gov/firm/summary/173961

**What changed in William Blair Investment Management, LLC's recent Form ADV filings?**
In the April 2026 filing data: Employees performing advisory functions went from 152 to 142.

## From the Form ADV filing

### Compensation (Item 5.E)
- A percentage of assets under your management
- Performance-based fees

### Custodians (Schedule D, Section 5.K(3))
- Bank of New York Mellon
- State Street Bank and Trust Company
- The 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.

### Regulatory assets under management (Item 5.F)
- Total: $65,596,131,787
- Discretionary: $65,596,131,787
- Non-discretionary: $0

### Clients (Item 5.D)

| Client type | Clients | Assets |
| --- | --- | --- |
| Individuals (other than high net worth individuals) | Fewer than 5 | $0 |
| High net worth individuals | 2 | $18,307,395 |
| Banking or thrift institutions | Fewer than 5 | $0 |
| Investment companies | 29 | $15,843,070,677 |
| Business development companies | 0 | $0 |
| Pooled investment vehicles (other than investment companies and business development companies) | 51 | $22,147,916,513 |
| Pension and profit sharing plans (but not the plan participants or government pension plans) | 73 | $11,851,584,002 |
| Charitable organizations | 68 | $2,337,130,386 |
| State or municipal government entities (including government pension plans) | 54 | $11,930,157,073 |
| Other investment advisers | 1 | $320,704,865 |
| Insurance companies | 4 | $23,539,301 |
| Sovereign wealth funds and foreign official institutions | 4 | $721,467,066 |
| Corporations or other businesses not listed above | 10 | $209,518,216 |
| Other | 386 | $192,736,293 |

### Advisory services (Item 5.G)
- 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

### Firm details
- Registered since: 2014 (11 years)
- Employees: 388 total, 142 performing advisory functions
- Wrap fee program participation: Yes
- States registered or notice-filed: AK, AL, AR, AZ, CA, CO, CT, DC, DE, FL, GA, HI, IA, ID, IL, IN, KS, KY, LA, MA, MD, ME, MI, MN, MO, MS, MT, NC, ND, NE, NH, NJ, NM, NV, NY, OH, OK, OR, PA, PR, RI, SC, SD, TN, TX, UT, VA, VI, VT, WA, WI, WV, WY
- Disclosures (Item 11): Reports 3 disclosure items on Form ADV Item 11.

### Item 11 questions answered yes
- 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. The detail of each yes answer is on the firm's SEC record: https://adviserinfo.sec.gov/firm/summary/173961

### Other offices (Schedule D, Section 1.F), as of the May 2026 filing
- Baltimore, MD
- Boston, MA
- New York, NY

### Websites listed on Form ADV (Item 1.I)
- [im.williamblair.com](https://im.williamblair.com)
- [open.spotify.com/show/7cd8ano4miwMxS7VTsuaAL](https://open.spotify.com/show/7cd8ano4miwMxS7VTsuaAL)
- [podcasts.apple.com/us/podcast/the-active-share/id1473139558](https://podcasts.apple.com/us/podcast/the-active-share/id1473139558)
- [tunein.com/podcasts/Business--Economics-Podcasts/The-Active-Share-p1234306](https://tunein.com/podcasts/Business--Economics-Podcasts/The-Active-Share-p1234306)
- [williamblair.com](https://williamblair.com)
- Facebook @WilliamBlairIM
- Instagram @williamblairim
- LinkedIn @william-blair-investment-management
- X @williamblairim
- YouTube @WilliamBlairInvMgmt

## Assets and staff over time

| Data period | Regulatory assets under management | Employees | Filing dated |
| --- | --- | --- | --- |
| October 2021 | $69,739,613,957 | 345 | July 19, 2021 |
| October 2022 | $79,683,544,422 | 389 | September 15, 2022 |
| October 2023 | $56,044,084,183 | 377 | July 14, 2023 |
| October 2024 | $67,246,025,476 | 372 | March 28, 2024 |
| October 2025 | $71,590,158,244 | 378 | July 16, 2025 |
| October 2026 | $65,596,131,787 | 388 | April 9, 2026 |

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.

## Changes in the filing (last 12 months)

### April 2026
- Employees performing advisory functions went from 152 to 142.

### March 2026
- Updated its list of owners and control persons (Schedule A).

### February 2026
- Updated its list of owners and control persons (Schedule A).

## Source

Form ADV as filed, October 2026. Values appear as filed. Cite as: AdvisorCensus. William Blair Investment Management, LLC (CRD 173961): Form ADV filing data as of October 2026.