Investor Presentaiton

Highlights Substantial Reserve Levels Reserve levels enhanced by credit protection and low loss loan categories Adjusted Total Loan ACL / Funded Loans: 1Q23 1.15% 0.06% EBOS³ 0.95% 0.97% 0.02% 0.12% Resi 0.20% 0.75% Total Loan ACL / Funded Loans 1,2 1 1.36% 0.21% WAL remains appropriately reserved, especially when considering credit protection from Credit Linked Notes (CLNs) and historically low loss loan categories Total Loan ACL / Funded Loans increased to 0.75% in Q1 as a result of heightened economic uncertainty • Total Loan ACL / Funded Loans less loans covered by CLNs is 0.95% Total Loan ACL / Funded Loans less loans covered by CLNs and select no-to- low-loss loan categories (EFR, Residential, and Mortgage Warehouse) is 1.36% • > 7x historical maximum annual loss rate4 Reserves are a multiple of average losses times portfolio duration • Estimated weighted average duration of the loan portfolio is < 4 years - Loans Covered by CLNs EFR Loans - Residential Loans - Mortgage Warehouse Loans • 2 3 4 5 Adj. total ACL covers > 20x historical average annual loss rate 4 x duration WA Western Alliance Bancorporation® Total Loan ACL includes allowance for unfunded commitments 2) Ratio includes an allowance for credit losses of $20.8 million as of March 31, 2023 related to a pool of loans covered under 4 separate credit linked notes 3) Early Buyout Loans are government guaranteed See slide 14 | 15

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