The U.K. Financial Conduct Authority (FCA) on Friday put the nail in the coffin of LIBOR, confirming the widely used benchmark interest rate will cease to be available in most forms at the end of this year.

The Dec. 31 expiration date for LIBOR, or the London Interbank Offered Rate, has been known for some time, as regulators in multiple countries have long advised registered firms to prepare for new reference rates. In July 2019, the Securities and Exchange Commission in the United States said the matter was becoming one of “urgency.”

“Today’s announcements mark the final chapter in the process that began in 2017, to remove reliance on unsustainable LIBOR rates and build a more robust foundation for the financial system,” said Bank of England Governor Andrew Bailey in a statement. “With limited time remaining, my message to firms is clear – act now and complete your transition by the end of 2021.”

Established by the FCA, LIBOR is a daily rate in multiple terms referencing multiple currencies that establishes an average interest rate used by banks as they borrow from one another. LIBOR is used extensively as a benchmark to determine lending terms on products ubiquitous to U.S. markets, such as corporate and municipal bonds, variable-rate loans, asset-backed securities, and many derivatives.

After discoveries of manipulation, U.K. authorities ultimately determined they would no longer require banks to provide the reporting necessary to support LIBOR after 2021.

That applies to all sterling, euro, Swiss franc, and Japanese yen settings, in addition to the one-week and two-month U.S. dollar settings, Friday’s press release confirmed. Remaining U.S. dollar settings may linger through June 30, 2023.

In the United States, the Financial Accounting Standards Board has issued optional guidance for accounting for the transition away from LIBOR and other reference rates to new benchmark rates. The guidance, which is temporary and only in effect during the reference rate transition period through Dec. 31, 2022, is intended to reduce the costs and complexities of accounting for reference rate reform.

The Fed-backed Secured Overnight Financing Rate (SOFR) is the favored alternative to LIBOR.