They are, and this is a full-on solvency issue, not just a liquidity one. Think of it this way: suppose you have an investment that pays out $100 in 2031, plus

They are, and this is a full-on solvency issue, not just a liquidity one. Think of it this way: suppose you have an investment that pays out $100 in 2031, plus a low rate of interest that due to interest rates increasing substantially in 2022 is now below what you can get from savings accounts or ultra-safe investments like Treasury bonds. That investment may have been worth $100 in 2021, but it's worth substantially less in 2023 because someone with $100 in 2023 could put it into those higher-interest investments and end up with a lot more money by 2031. However, banking regulations allow banks to not immediately recognize that drop in the value of their reserves by claiming they'd hold the investments to maturity.