UBS AG, Switzerland's biggest bank, may be fined more than $1 billion by U.S. and U.K. regulators for trying to rig global interest rates, more than double the amount levied against Barclays Plc, according to a person familiar with the probe.

The fines from the U.S. Commodity Futures Trading Commission, the U.K. Financial Services Authority and the U.S. Department of Justice may be announced as early as next week, said the person, who asked not to be identified because the information isn't public. The final figures are still being negotiated and could change, three people familiar with the probes said.

Global authorities are investigating claims that more than a dozen banks altered submissions used to set benchmarks such as the London interbank offered rate to profit from bets on interest-rate derivatives or make the lenders' finances appear healthier. Barclays, the U.K.'s second-biggest bank, agreed to pay 290 million pounds ($467 million) in June to resolve the U.S. and U.K. Libor probes.