0000872649 2025-09-30 2025-09-30 0000872649 lsfii:S000006705Member 2025-09-30 2025-09-30 false 2025-09-30 497 0000872649 LOOMIS SAYLES FUNDS II 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 July 1, 2026 to the Fund’s Prospectus, dated February 1, 2026, as may be revised or </span></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">supplemented from time to time. </span></div><div style="margin-top:12pt;margin-bottom:0pt;font-size:10pt;font-family:times new roman;font-weight:bold;text-align:center;">LOOMIS SAYLES SMALL CAP GROWTH 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 second footnote under the Annual Fund Operating Expenses table within the section “Fund Fees &amp; Expenses” in the Fund’s Summary Prospectus is restated as follows: </span></div><div style="margin-top:6pt;margin-bottom:0pt;font-size:10pt;font-family:times new roman;">Effective July 1, 2026, Loomis, Sayles &amp; Company, L.P. has given a binding contractual undertaking to the Fund to limit the amount of the Fund’s total annual fund operating expenses to 0.94%, 1.19% and 0.89% of the Fund’s average daily net assets for Institutional Class shares, Retail Class shares, and Class N shares, respectively, exclusive of brokerage expenses, interest expense, taxes, acquired fund fees and expenses, organizational and extraordinary expenses, such as litigation and indemnification expenses. This undertaking is in effect through January 31, 2028. </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 July 1, 2026 to the Fund’s Prospectus, dated February 1, 2026, as may be revised or </span></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">supplemented from time to time. </span></div><div style="margin-top:12pt;margin-bottom:0pt;font-size:10pt;font-family:times new roman;font-weight:bold;text-align:center;">LOOMIS SAYLES SMALL CAP GROWTH 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 second footnote under the Annual Fund Operating Expenses table within the section “Fund Fees &amp; Expenses” in the Fund’s Summary Prospectus is restated as follows: </span></div><div style="margin-top:6pt;margin-bottom:0pt;font-size:10pt;font-family:times new roman;">Effective July 1, 2026, Loomis, Sayles &amp; Company, L.P. has given a binding contractual undertaking to the Fund to limit the amount of the Fund’s total annual fund operating expenses to 0.94%, 1.19% and 0.89% of the Fund’s average daily net assets for Institutional Class shares, Retail Class shares, and Class N shares, respectively, exclusive of brokerage expenses, interest expense, taxes, acquired fund fees and expenses, organizational and extraordinary expenses, such as litigation and indemnification expenses. This undertaking is in effect through January 31, 2028. </div> 2026-02-01