Prospectus by Investment Company (Form 497)

Supplement dated June 22, 2026 to the Statement of Additional Information, dated February 1, 2026, as may be revised or supplemented from time to time, for the following fund:

LOOMIS SAYLES GLOBAL BOND FUND

(the "Fund")

Effective July 1, 2026, the Fund's Board of Trustees approved a proposal to simplify the Fund's management fee rate. The management fee rate will be 0.52% on the first $1 billion of assets, 0.48% on the next $1 billion in assets and 0.40% of amounts in excess of $2 billion in assets. The table regarding advisory fee rates within the sub-section "Advisory Agreements" in the section "Investment Advisory and Other Services" is amended and restated with respect to the Fund as follows:

Supplement dated June 22, 2026 to the Statement of Additional Information, dated May 1, 2026, as may be revised or supplemented from time to time, for the following fund:

LOOMIS SAYLES INCOME FUND

(the "Fund")

Effective July 1, 2026, the Fund's Board of Trustees approved a proposal to simplify the Fund's management fee rate. The management fee rate will be 0.59% of the first $3 billion of assets and 0.48% of the amounts in excess of $3 billion in assets. The table regarding advisory fee rates within the sub-section "Advisory Agreements" in the section "Investment Advisory and Other Services" is amended and restated with respect to the Fund as follows: