William Blair Ultra-Short Duration Bond Fund Class N 

The investment seeks to maximize total return; total return includes both income and capital appreciation. Under normal market conditions, the fund invests at least 80% of its net assets (plus the amount of any borrowings for investment purposes) in bonds. For purposes of this policy, “bonds” include all types of fixed income instruments. The fund invests primarily in investment grade debt securities rated in the highest three categories by at least one nationally recognized statistical rating organization. The fund invests in U.S. dollar-denominated securities.