The value of the world’s main financial benchmark—the London Interbank Offered Rate, or Libor—has been thrown in doubt

Libor, the rate at which banks lend on an unsecured basis to one another, is set by the British Bankers’ Association. The BBA says some banks have understated the rate they pay on loans to avoid appearing in trouble. That means that Libor—which is the benchmark for most loans, many mortgages and a big chunk of interest-rate derivatives—could be too low. If it shoots up, what will that mean for my investments? For my cost of capital?