Weaning off the scandal-plagued LIBOR benchmark is a gigantic problem for global rates markets, one that increasingly looks too burdensome for a single replacement to handle in the United States.

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

But the Bank for International Settlements, which serves as the bank for central banks, said in March that a one-size-fits-all alternative may be neither feasible nor desirable. Although SOFR solves the rigging problem, it doesn't help participants gauge how stressed global funding markets are. That means SOFR is likely to coexist with something else.