(Bloomberg) -- The push to replace Libor is heating up, with the American Financial Exchange completing its first interest-rate swap linked to the alternative Ameribor benchmark.The self-regulated exchange, which facilitates the determination of Ameribor, said it completed a transaction worth a notional $24 million on Tuesday. The deal “marks an important moment for Ameribor as it becomes a viable standard for swap markets,” the exchange said.Ameribor is among a handful of rates vying for market share as regulators prepare to retire the beleaguered London interbank offered rate. It’s calculated from the actual borrowing costs between the mostly small and midsize banks that are members of the American Financial Exchange.For now, the Secured Overnight Financing Rate is the main replacement for dollar Libor, which underpins roughly $200 trillion of securities. Libor’s administrator the ICE Benchmark Administrator introduced its own Bank Yield Index in January 2019 as a potential replacement for lending activity tied to Libor.After years of steadfastly maintaining that the benchmark would be phased out by the end of 2021, regulators abruptly shifted course on Monday, pushing back the timeline for abandoning some of the discredited benchmark’s key tenors.Regulators prefer SOFR to Libor because a vast amount of trading underpins the benchmark -- more than $1 trillion on most days -- compared with an estimated $500 million for three-month dollar Libor. That makes it a truer reflection of the cost of capital and less susceptible to corruption.The IBA’s Bank Yield Index has multiple tenors as well as the credit component SOFR lacks, which means it reflects banks’ credit risk when they lend.(Adds context on SOFR and Bank Yield Index in final two paragraphs.)For more articles like this, please visit us at bloomberg.comSubscribe now to stay ahead with the most trusted business news source.©2020 Bloomberg L.P.