[hirako2000]

Not an HTM certified, not even a practitioner here. But it's also an accounting question. The way it's done: asset is valued per maturation. It would mudd the water even further I think to have the quarterly reflect the "at current market" value. Things go up and down. What matters is how you close (realised gains or loss), and, at SVB's demise: your cashflow.

No cash? Then sell your assets. Creditors/depositors ain't gonna wait. Realised loss? That's your balance going down in true accounting terms now. Accountings get disclosed? Those quarterly release are mandatory for all publicly trading company: that could cause worry among investors, and in the case of a bank a panic a bank run.

What a market valuation made at each quarter could achieve is give a momentarily evaluation of what a fund's assets is made of if they were to liquidate right then, or that day. But it isn't how it works*

It does work for goods though, amortization is accounted for and a well oiled exercise. Futures, bonds, stocks? Good luck with that. If we could predict the future the game would be a whole lot different.