Earlier quoted context omitted.
In SVB's case, can't you cover depositors simply by holding their assets to maturity and waiting for them to be repaid? SVB couldn't do that because there was a run that was forcing them to sell early, in unfavorable conditions.
This doesn't make sense though. Sure they would have to take a haircut on those securities thanks to the fed jacking up the interest rate so much, but if you offer the right price they should still sell. Investing involves risk. Sometimes that means losing money, even if you are the bank.
The reason a $100 par bond paying 2% sells for (I don't know, say) $87 when interest rates are (I don't know, say) 5% isn't that the original bond is impaired. It's that the same $100 buys you a bond that pays 3% better, so nobody will buy the bond without a discount.
But the bank doesn't normally sell the bond to begin with. That's why people say banks "borrow short and lend long". What the bank is supposed to do is hold the bond until it matures and is paid back in full. The only reason SVB can't do that is that all its depositors simultaneously demanded their money bank, so it couldn't wait the bonds out. But other institutions can do that waiting.