NEW YORK CITY—Libor, an index that underpins $350 trillion in financial contracts, has been a benchmark for global borrowing for nearly half a century. But it will soon go the way of BOAC and the Beatles, two British institutions that were still recent history when Libor was devised. Will the sunset of Libor in 2021 plunge lenders and borrowers into darkness and confusion? And what will take its place?

In the view of Jillian Mariutti, director at Mission Capital Advisors, the answer to the first question is no, because the writing has been on the wall since the Libor manipulation scandal of 2012.

As for the second question, the successor to Libor—at least for the US market—is likely to be the Secured Overnight Funding Rate (SOFR), which the Federal Reserve Bank of New York is expected to begin publishing in mid-2018.