Western Alliance Bank Routing Number - The Bank That Stared Down a Contagion and Survived

Five days in March that tested everything

On March 10, 2023, Silicon Valley Bank failed. On March 12, Signature Bank was seized. By March 13, Western Alliance Bank's stock had fallen from above $70 in early February to under $12 intraday — a drop of over 80% in weeks — as short sellers targeted it as the next to go.

It didn't fall. CEO Kenneth Vecchione and Western Alliance's management team released daily deposit data publicly to demonstrate the bank wasn't experiencing the outflows that killed SVB and Signature. The FDIC and Federal Reserve's emergency actions helped, but Western Alliance's survival came down to its fundamentals: sophisticated commercial clients looked at the balance sheet and decided it was sound, even as the stock said otherwise.

Why Western Alliance wasn't the next SVB

The comparison to SVB was superficial. SVB had concentrated its balance sheet in a single industry and a single geography. Western Alliance ran a diversified commercial banking platform across multiple industries and states — technology banking was one segment alongside hotel franchise lending, municipal finance, and national business lending. When SVB's concentrated deposit base fled in 48 hours, Western Alliance's held because no single client segment was large enough to trigger a fatal run.

Western Alliance's routing number

Western Alliance Bank's routing number is 122105612. The 122 prefix ties to the Federal Reserve Bank of San Francisco, reflecting the bank's Arizona charter. This routing number applies to all Western Alliance deposit accounts — personal and business checking, savings, and money market accounts — and works for ACH transfers, direct deposits, and domestic wire transfers.

Western Alliance operates through several banking divisions, including Alliance Bank of Arizona, Bank of Nevada, and First Independent Bank of Nevada. Accounts held at any of these divisions generally use 122105612, but confirm through your specific online banking portal or account statement before setting up a transfer.

Phoenix as a banking headquarters

Arizona has become a significant financial services hub — business-friendly regulation, a growing population, and a central position between the California and Texas economies have pulled in banks, fintechs, and corporate relocations. Western Alliance grew alongside that shift, expanding from roughly $4 billion in assets in 2012 to over $70 billion by 2023, making it one of the fastest-growing banks in the country before March 2023 interrupted that trajectory. Post-crisis, growth has resumed with a sharper focus on deposit diversification and liquidity management.

Resilience as a design principle

Western Alliance survived a crisis that took down two peers by having sound fundamentals and the transparency to prove it in real time. Slash is built on the same logic — real-time spend tracking, automated policy enforcement on corporate cards, and instant expense reporting give businesses full visibility into what they're actually spending, not what they think they're spending.