# EDGAR Filing Document

**Accession Number:** 0000822632
**File Stem:** 0001193125-26-010063
**Filing Date:** 2026-1
**Character Count:** 2233
**Document Hash:** adba05902c40aa0239f87c4f490f9b2e
**Contains OCR:** False
**Source Format:** 

## Filing Content

## Filing Summary
**0001193125-26-010063.hdr.sgml**: 20260112

**ACCESSION NUMBER**: 0001193125-26-010063

**CONFORMED SUBMISSION TYPE**: 497K

**PUBLIC DOCUMENT COUNT**: 1

**FILED AS OF DATE**: 20260112

**DATE AS OF CHANGE**: 20260112

**EFFECTIVENESS DATE**: 20260112

**FILER**: 

**COMPANY DATA:**
- **COMPANY CONFORMED NAME:** WILLIAM BLAIR FUNDS
- **CENTRAL INDEX KEY:** 0000822632

**ORGANIZATION NAME:**
- **EIN:** 000000000
- **FISCAL YEAR END:** 1231

**FILING VALUES:**
- **FORM TYPE:** 497K
- **SEC ACT:** 1933 Act
- **SEC FILE NUMBER:** 033-17463
- **FILM NUMBER:** 26525395

**BUSINESS ADDRESS:**
- **STREET 1:** 150 NORTH RIVERSIDE PLAZA
- **CITY:** CHICAGO
- **STATE:** IL
- **ZIP:** 60606
- **BUSINESS PHONE:** 3123648000

**MAIL ADDRESS:**
- **STREET 1:** 150 NORTH RIVERSIDE PLAZA
- **CITY:** CHICAGO
- **STATE:** IL
- **ZIP:** 60606

**FORMER COMPANY:**
- **FORMER CONFORMED NAME:** WILLIAM BLAIR MUTUAL FUNDS INC
- **DATE OF NAME CHANGE:** 19960112

**FORMER COMPANY:**
- **FORMER CONFORMED NAME:** BLAIR WILLIAM READY RESERVES INC
- **DATE OF NAME CHANGE:** 19920316

## Series and Classes Contracts Data

### William Blair Institutional International Growth Fund (Series ID: S000008605)

| Class ID   | Class Name          | Ticker Symbol   |
|:---|:---|:---|
| C000023546 | Institutional Class | WBIIX           |

**WILLIAM BLAIR FUNDS** 

**William Blair International Growth Fund** 

**William Blair Institutional International Growth Fund** 

**(each a "Fund" and collectively, the "Funds")** 

Supplement dated January 12, 2026 to each Fund's Summary Prospectus dated May 1, 2025, and the

Funds' Prospectus, dated May 1, 2025, as supplemented

Effective February 1, 2026:

The information below replaces similar disclosure in the "Management" section of each Fund's Summary Prospectus and the "Summary – Management" sections for each Fund in the Prospectus as follows:

**Portfolio Managers.** Simon Fennell and Andrew Siepker, Partners of the Adviser, co-manage the Fund. Mr. Fennell has co-managed the Fund since 2013. Mr. Siepker has co-managed the Fund since 2022.

**WILLIAM BLAIR FUNDS** 

150 North Riverside Plaza

Chicago, Illinois 60606

Please retain this supplement for future reference.