AEIS: Other company developments

Item 8.01. Other Events. On May 13, 2026, Advanced Energy Industries, Inc. issued a press release announcing the pricing of an offering of $1 billion aggregate principal amount of its 0% Convertible Senior Notes due 2031 in a private transaction that is exempt from the registration requirements of the Securities Act of 1933, as amended. 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. The following exhibits are filed with this report. Exhibit Number ​ ​ ​ Description 99.1 Press Release dated May 13, 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. ​ ​ ADVANCED ENERGY INDUSTRIES, INC. ​ /s/ Paul Oldham Date: May 13, 2026 Paul Oldham ​ Chief Financial Officer & Executive Vice President ​ ​ ​