AEIS: Other company developments

Item 8.01. Other Events. On June 12, 2026, Advanced Energy Industries, Inc. issued a press release announcing that it had issued a notice of redemption to redeem on September 23, 2026, all $136,709,000 of its remaining outstanding 2.50% Convertible Senior Notes due 2028. A copy of the press release is attached hereto as Exhibit 99.1 and incorporated by reference herein. Item 9.01 Financial Statements and Exhibits. ​ (d) Exhibits ​ Exhibit Number Description ​ ​ ​ 99.1 Press Release dated June 12, 2026 104 Cover Page Interactive Data File (embedded within the Inline XBRL document). ​ ​ ​ ​ ​ ​ SIGNATURES Pursuant to the requirements of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned hereunto duly authorized. ​ ​ ​ ​ ​ ​ ​ ​ /s/ Paul Oldham Date: June 12, 2026 Paul Oldham ​ Executive Vice President and Chief Financial Officer ​ ​ ​ ​ ​ ​ ​ ​