Its accounting nonsense basically. Legally banks are allowed to value assets like bonds which they intend to hold to maturity at the original purchase value, be

Its accounting nonsense basically. Legally banks are allowed to value assets like bonds which they intend to hold to maturity at the original purchase value, because well, eventually they should get their money back. Issues only arise when they are forced to sell these assets because then they must acknowledge the fact they're not actually worth as much as the bank says they are. My guess is that mark-to-market the value of SVB UK's assets don't exceed total liabilities, in which case it makes no sense to purchase for their assets alone.