Out of 563 previous bank failures going back to October 2000, only 31 did not have an acquiring institution lined up (https://www.fdic.gov/resources/resolutions/bank-failures/fai...)
Usually the FDIC will sell the assets and liabilities of the failed bank to a healthy bank, sometimes at a negative value (paying the acquiring bank to receive the assets) and then also making the acquiring bank whole on losses of the assets
SIVB is upside down on various interest bearing assets like MBS and US Treasuries. In a normal case, it'd be cheaper for the FDIC to just make up those losses than directly make depositors whole, so they do that
In this case, given how little of SIVB's deposits are actually insured, the scale of the run before they got the doors closed, and the amount of losses they are going to take in the assets, the FDIC obviously wasn't willing to backstop the losses and no one was willing to take the risk
Depositors are definitely taking a haircut on this one