Unconstrained Bond Series (Class I, Class S, Class W and Z) (the “Series”)

Supplement dated July 15, 2025 to:

This supplement provides new and additional information beyond that contained in the Summary Prospectus and Prospectus, and should be read in conjunction with the Summary Prospectus and Prospectus.

Effective July 15, 2025 (the “Effective Date”), the Series’ secondary benchmark will change as follows:

Accordingly, as of the Effective Date, the Summary Prospectus and Prospectus are hereby amended and supplemented as follows:

In the “Summary of Past Performance” section of the Summary Prospectus, and the corresponding section of the Prospectus, the “Average Annual Total Returns” table is hereby deleted and replaced with the following: