Secession-minded Scots and diverging interest-rate outlooks have benefited at least one part of financial markets. They have eased the recent drought in currency trading with some platforms witnessing record volumes.

CLS Group Holdings AG, the bank-owned firm that sits at the heart of global currency markets, processed more than 2 million payments Wednesday, the most since its creation in 2002, according to an emailed statement. The $10.1 trillion value of the transactions narrowly missed CLS's record of $10.3 trillion set on March 19, 2008.

The rebound in activity will be welcomed by everyone who makes money from trading, including Wall Street banks and electronic platforms. Betting on currencies has picked up amid mounting evidence that interest rates will climb in the U.S. and the U.K. long before they do in Japan and the euro area. Thursday's referendum on independence in Scotland has led to a spike in activity as companies and investors seek to protect themselves against a possible "yes" vote.