144 0001289226 XXXXXXXX LIVE 0000811596 Kaiser Aluminum 001-09447 1550 West McEwen Drive Suite 500 Franklin TN 37067 6292527040 Brett Wilcox Board Member Common UBS Financial Services Inc

1000 Harbor Blvd 3rd Floor Weehawken NJ 07086

15000 2625000 16340606 04/27/2026 Nasdaq Common 06/04/2013 RSU Kaiser Aluminum N 1478 06/04/2013 N/A common 06/04/2014 RSU Kaiser Aluminum N 1384 06/04/2014 N/A Common 06/02/2015 RSU Kaiser Aluminum N 1158 06/02/2015 N/A Common 05/26/2017 RSU Kaiser Aluminum N 1078 05/26/2017 N/A Common 06/04/2016 RSU Kaiser Aluminum N 373 06/04/2016 N/A Common 06/06/2019 RSU Kaiser Aluminum N 336 06/06/2019 N/A Common 06/14/2019 RSU Kaiser Aluminum N 1001 06/14/2019 N/A Common 06/06/2020 RSU Kaiser Aluminum N 1185 06/06/2020 N/A Common 06/10/2020 RSU Kaiser Aluminum N 491 06/10/2020 N/A Common 06/03/2021 RSU Kaiser Aluminum N 266 06/03/2021 N/A Common 06/10/2021 RSU Kaiser Aluminum N 1756 06/10/2021 N/A Common 06/02/2022 RSU Kaiser Aluminum N 611 06/02/2022 N/A Common 06/03/2022 RSU Kaiser Aluminum N 952 06/03/2022 N/A Common 06/02/2023 RSU Kaiser Aluminum N 229 06/02/2023 N/A Common 06/07/2024 RSU Kaiser Aluminum N 2060 06/07/2024 N/A Common 06/11/2024 RSU Kaiser Aluminum N 642 06/11/2024 N/A Y Brett Wilcox is on the board of Kaiser Aluminum, The Brett E. Wilcox Trust dtd 07/02/2019 is the seller. 04/27/2026 /s/JOSEPH CASSIDY, for UBS Financial Services Inc, as attorney-in-fact for Brett Wilcox