Supplement dated June 11, 2026 to the Fund’s Prospectus and Statement of Additional Information

(“SAI”), each dated May 7, 2026, as may be revised or supplemented from time to time.

LOOMIS SAYLES CREDIT INCOME OPPORTUNITIES FUND

(the “Fund”)

Effective June 30, 2026, Christopher J. Romanelli will join the portfolio management team of the Loomis Sayles Credit Income Opportunities Fund.

Matthew J. Eagan, Peter S. Sheehan, and Eric Williams will remain as portfolio managers of the Loomis Sayles Credit Income Opportunities Fund.

Accordingly, effective June 30, 2026, the subsection “Portfolio Managers” under the section “Management of the Fund” in the Prospectus is revised to include the following:

Christopher J. Romanelli, CFA® has served as a portfolio manager of the Fund since 2026. Mr. Romanelli, Portfolio Manager of Loomis Sayles, began his investment career in 2005 and joined Loomis Sayles in 2010. He received a B.S. from Gordon College, and an M.S. from Boston University. Mr. Romanelli has over 21 years of investment experience.

Effective June 30, 2026, the sub-sections “Portfolio Managers’ Management of Other Accounts” and “Portfolio Managers’ Ownership of Fund Shares” within the section “Portfolio Management Information” of the SAI is revised to include the following:

Portfolio Managers’ Management of Other Accounts

The following table provides information on the other accounts managed by the portfolio managers as of April 30, 2026:

 

     Registered Investment
Companies		      Other Pooled Investment
Vehicles		      Other Accounts  
   Other Accounts
Managed		      Advisory Fee
is Based on
Performance		      Other
Accounts
Managed		      Advisory fee is
Based on
Performance		      Other Accounts
Managed		      Advisory Fee
is Based on
Performance		  

Name of
Portfolio
Manager

    # of
Accts		      Total
Assets		      # of
Accts		      Total
Assets		      # of
Accts		      Total
Assets		      # of
Accts		      Total
Assets		      # of
Accts		      Total
Assets		      # of
Accts		      Total
Assets		  

Matthew J. Eagan

      21      $ 39.5 billion        0      $ 0        35      $ 14.0 billion        0      $ 0        97      $ 32.2 billion        3      $ 354.2 million  

Christopher Romanelli

      1      $ 81.6 million        0      $ 0        1      $ 72.5 million        0      $ 0        2      $ 857.0 million        0      $ 0  

Peter S. Sheehan

      6      $ 1.2 billion        0      $ 0        19      $ 1.4 billion        0      $ 0        34      $ 6.0 billion        3      $ 354.2 million  

Eric Williams

      5      $ 1.2 billion        0      $ 0        19      $ 1.4 billion        0      $ 0        28      $ 5.7 billion        3      $ 354.2 million