More problematically it would create uncontrolled swings in their regulatory capital ratios. But those assets are typically hedges against long term fixed rate

More problematically it would create uncontrolled swings in their regulatory capital ratios. But those assets are typically hedges against long term fixed rate bonds issued by the bank, or are funded by a diversified (and mostly retail, ie more stable) deposit base with a large enough liquidity pool to sustain a period of stress, as mandated by liquidity regulations.