The immediate threat to banks is a fall in the market value of assets that banks hold. As yields of government bonds and other fixed-income securities rise, their prices fall. Because the amounts of outstanding debt are so large, the effects can be big. In its latest annual report the Bank for International Settlements, the Basel-based bank for central banks, reckons that a hypothetical three-percentage-point increase in yields across all bond maturities could result in losses to all holders of government bonds equivalent to 15-35% of GDP in countries such as France, Italy, Japan and Britain (see chart).
Here again the effect on banks would vary widely from country to country. Government bonds account for less than 2% of the assets held by British banks, compared with about 25% of assets in the case of Japanese banks. But simply looking at holdings of government bonds probably understates the risk to banks of an upward lurch in yields, since they hold many other fixed-income assets that would also fall in value. Some 40% of British banks’ assets would have to be revalued if interest rates were to rise abruptly, according to the Bank of England. Furthermore, banks may be indirectly exposed to losses on fixed-income securities through other channels—loans to clients that are big holders of these instruments, say, or changes in the value of securities that are held as collateral.
A third risk to banks from higher rates is that more of their customers will struggle to repay their loans. Quantifying this risk is difficult since loan losses are influenced not just by interest rates but also by economic growth and employment, both of which would need to improve for central bankers to dial back their interventions. Even so, there are worrying signs. In Britain almost a fifth of secured loans have gone to households that have less than £200 ($307) a month left after paying essential costs, according to the Bank of England. Higher rates could push many into default. The dilemma for policymakers is that keeping rates low for long is dangerous. So is letting them rise too quickly.