(Bloomberg) -- Regulators kicked off the final countdown for the London interbank offered rate Friday, ordering banks to be ready for the end of a much maligned benchmark that’s been at the heart of the international financial system for decades.The U.K. Financial Conduct Authority confirmed that the final fixings for most rates will take place at end of this year, with just a few key dollar tenors set to linger for a further 18 months.The move comes in the wake of major manipulation scandals and the drying up of trading used to inform the rates, which are linked to everything from credit cards to leveraged loans. Global regulators have made a concerted effort to wind down the benchmark in 2021, with the Federal Reserve and others pushing market participants toward a slew of alternatives.“Outside the U.S. dollar markets, this marks the end game,” said Claude Brown, a partner at Reed Smith LLP in London. “The rate that linked the world, and then shocked the world, will leave this world in 2021.”Libor is deeply embedded in financial markets. Some $200 trillion of derivatives are tied to the U.S. dollar benchmark alone and most major global banks will spend more than $100 million this year preparing for the switch. Other players -- from corporations to hedge funds -- will also be affected, with many only beginning to shift from legacy contracts.Bank of England Governor Andrew Bailey said this was now the “final chapter,” and there’s no excuse for delays.The BOE will hold executives to account for progress in the transition under the U.K.’s regulatory regime for senior managers, according to people familiar with the matter. If firms fail to take appropriate steps, there is the potential for measures such as capital sanctions, though these would come further down the line.Progress toward replacement benchmarks, such as the Secured Overnight Financing Rate in the U.S. and the Tokyo Overnight Average Rate in Japan, has been sluggish, and there are hopes Friday’s announcement could accelerate the process -- particularly in the vast global derivatives market.“This was the much anticipated final piece of clarity the market needed to really kick on,” said Kari Hallgrimsson, co-head of EMEA rates at JPMorgan Chase & Co. “We would expect liquidity for trading the new rates to keep increasing from here on out.”Friday’s decision is a cessation event and locks in the benchmark’s fallback spread calculations, which for dollar Libor will be added to SOFR, the main U.S. replacement. Where firms have adhered to International Swaps and Derivatives Association’s Libor protocol, their contracts will automatically transition to replacement rates the moment Libor ends, avoiding a cliff-edge scenario.“This is a big deal because anyone trying to think about transferring from Libor to SOFR risk, or thinking about what the economics of relying on the Libor fallbacks will be, now has certainty with regards to what the spreads will be,” said Blake Gwinn, head of front-end rates strategy at NatWest Markets Plc.The delay in the most-used dollar Libor tenors -- notably the three-month benchmark -- is a concession to market concerns, but regulators remain adamant that dollar Libor shouldn’t be used for new contracts after 2021. Firms should expect further engagement from their supervisors to ensure timelines are met, the FCA warned.The Fed, for its part, is intensifying its scrutiny of banks’ efforts to shed their reliance on Libor, and has begun compiling more detailed evidence on their progress.While speculation about the announcement’s timing jolted the eurodollar market in December, the market reaction on Friday was subdued. The spread between June 2023 and September 2023 Eurodollars widened one basis point, as did the difference between December 2021 and March 2022 short sterling contracts.“Now the deadlines and spread adjustments for the fallback rates are fixed, firms can push forward,” International Swaps and Derivatives Association Chief Executive Officer Scott O’Malia said in a statement. “There’s not much time left.”The FCA also detailed proposals to deal with the most troublesome loans and securitizations that can’t be switched to replacement rates. The regulator will consult on synthetic Libor -- which doesn’t rely on bank panel data -- for the sterling and yen benchmarks, and will continue to consider the case for using these powers for some dollar Libor settings.Worries are mounting that hundreds of billions of dollars of these legacy contracts will never be able to transition, even with the extension of certain dollar Libor tenors. This will present a key challenge to banks, regulators and lawmakers in the months ahead.“Some cash products have not embraced Libor and the clock is ticking loudly,” said Priya Misra, global head of interest rate strategy at TD Securities. “A lot of them will mature by June 2023, but there will be a lot left over after that.”(Updates with BOE in seventh paragraph, additional reaction from analysts.)For more articles like this, please visit us at bloomberg.comSubscribe now to stay ahead with the most trusted business news source.©2021 Bloomberg L.P.