Weaning off the scandal-plagued LIBOR benchmark is a giganticproblem for global rates markets, one that increasingly looks tooburdensome for a single replacement to handle in the UnitedStates.

Global regulators decided to move away from the London interbankoffered rate—a vital part of the financial system given that it'slinked to, at last count, about $350 trillion of loans,derivatives, and other instruments across various currencies—afterprosecutors found that banks around the world manipulated it. Italso didn't help that volumes underlying the benchmark dried up.For the U.S., a group backed by the Federal Reserve pickedsomething called the Secured Overnight Financing Rate, or SOFR. It launched a year ago Wednesday.

But the Bank for International Settlements, which serves as thebank for central banks, said in March that a one-size-fits-allalternative may be neither feasible nor desirable. Although SOFRsolves the rigging problem, it doesn't help participants gauge howstressed global funding markets are. That means SOFR is likely tocoexist with something else.