Silicon Valley Bank, reason behind the default

Silicon Valley Bank is the largest bank to fail since the 2008 financial crisis. The primary reason for the failure of SVB was their choice to invest their customers' deposits in treasury bonds, which are highly impacted by shifts in interest rates. 

It bought government bonds with fixed interest rates and as the Fed raised rates, those bonds lost value. Silicon Valley Bank had $80 billion in bonds with an average yield of 1.5%. No one wants bonds yielding 1.5% when the current market is selling bonds with yields over 5%.