X0609 4 2026-04-29 0000811596 KAISER ALUMINUM CORP KALU 0001972491 Grimley Richard P. false 1550 WEST MCEWEN DRIVE, SUITE 500 FRANKLIN TN 37067 true false false false false Common Stock, par value $0.01 per share 2026-04-29 4 S false 1524 171.52 D 4578 D Represents the sale of 1,524 shares in multiple transactions, ranging from $171.25 to $171.74 per share, resulting in a weighed average sale price of $.171.52 per share. The reporting person undertakes to provide upon request by the SEC staff, the Registrant, or a security holder of the Registrant, full information regarding the number of shares sold at each separate price within the range. /s/ Cherrie I. Tsai, with power of attorney for Richard P. Grimley 2026-05-01