The assets are going to the fed and the fed is giving depositors par, the fed will then hold the asset to maturity.

If a bank decides to buy assets and liabilities of sivb or signature they will assume both the assets and liabilities. They won’t benefit from this.

The fed could have done nothing in which case by Wednesday there likely would have been a bank holiday as every depositor moved money out of regional banks to the four banks (they are essentially the fed with retail branches).

So you could argue this hurt the big banks because it didn’t give them more deposit base.