0000917469 2025-02-01 2025-02-01 0000917469 lsfi:S000006639Member 2025-02-01 2025-02-01 iso4217:USD pure false 2025-05-28 2024-09-30 497 0000917469 LOOMIS SAYLES FUNDS I N-1A <div style="margin-top:0pt;margin-bottom:0pt;font-size:10pt;font-family:times new roman;text-align:center;"><span style="font-style:italic">Supplement dated May 28, 2025 to the Summary Prospectus and Prospectus dated February 1, 2025, as may be revised or supplemented from time to time, for the following fund:</span></div><div style="margin-top:24pt;margin-bottom:0pt;font-size:10pt;font-family:times new roman;font-weight:bold;text-align:center;">LOOMIS SAYLES SECURITIZED ASSET FUND </div><div style="margin-top:0pt;margin-bottom:0pt;font-size:10pt;font-family:times new roman;font-weight:bold;text-align:center;">(the “Fund”) </div><div style="margin-top:12pt;margin-bottom:0pt;font-size:10pt;font-family:times new roman;font-weight:bold;"><span style="font-style:italic">Effective immediately, the fourth sentence in the first paragraph in the subsection “Principal Investment Strategies” within both the “Investments, Risks and Performance” section of the Fund Summary and the “More Information about Investment Strategies” section of the Fund Prospectus is amended and restated as follows: </span></div><div style="margin-top:6pt;margin-bottom:0pt;font-size:10pt;font-family:times new roman;">It is expected that a majority of the Fund’s securities will have credit quality equal to the credit rating of the U.S. Government’s long-term debt by at least one of the rating agencies at the time of purchase. </div> <div style="margin-top:0pt;margin-bottom:0pt;font-size:10pt;font-family:times new roman;text-align:center;"><span style="font-style:italic">Supplement dated May 28, 2025 to the Summary Prospectus and Prospectus dated February 1, 2025, as may be revised or supplemented from time to time, for the following fund:</span></div><div style="margin-top:24pt;margin-bottom:0pt;font-size:10pt;font-family:times new roman;font-weight:bold;text-align:center;">LOOMIS SAYLES SECURITIZED ASSET FUND </div><div style="margin-top:0pt;margin-bottom:0pt;font-size:10pt;font-family:times new roman;font-weight:bold;text-align:center;">(the “Fund”) </div><div style="margin-top:12pt;margin-bottom:0pt;font-size:10pt;font-family:times new roman;font-weight:bold;"><span style="font-style:italic">Effective immediately, the fourth sentence in the first paragraph in the subsection “Principal Investment Strategies” within both the “Investments, Risks and Performance” section of the Fund Summary and the “More Information about Investment Strategies” section of the Fund Prospectus is amended and restated as follows: </span></div><div style="margin-top:6pt;margin-bottom:0pt;font-size:10pt;font-family:times new roman;">It is expected that a majority of the Fund’s securities will have credit quality equal to the credit rating of the U.S. Government’s long-term debt by at least one of the rating agencies at the time of purchase. </div> 2025-05-28 2025-02-01