Royal Bank of Scotland Group PLC was fined $43 million, the largest U.K. regulatory penalty against a financial institution, for giving confidential pricing data to Barclays PLC.

Two employees on RBS' professional practices coverage team disclosed confidential pricing data to their counterparts at Barclays from October 2007 to at least February 2008, the Office of Fair Trading said Tuesday in a statement.

Barclays isn't likely to be fined because it brought the matter to the antitrust regulator's attention, the OFT said.

The fine was reduced because RBS cooperated with the probe, the OFT said.

This situation is a "deeply regrettable and isolated case," RBS said in a statement.

One of the employees who was involved left the bank, and the other faces suspension and further investigation, RBS said.

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