The Financial Conduct Authority confirmed that all nine banks have now completed their sales determinations of customers who joined the review into lenders mis-selling complex derivatives to SMEs before March 2014.
According to the regulator, banks, such as Barclays, the Royal Bank of Scotland, Lloyds Banking Group and HSBC have delivered redress letters to all but a handful of these customers.
IRSAs are contracts between banks and customers where typically one side pays a floating or variable rate of interest and receives a fixed rate of interest payments in exchange.
Such contracts are used to hedge against extreme movements in market interest rates over a given period. Companies that saw the value of these products move against them as rates fell during the recession now owe banks inordinate sums of money in yearly interest payments.
The FCA said banks are paying out £1.5bn (€1.9bn, $2.4bn) in redress to SMEs that were mis-sold interest rate swap agreements (IRSA), which includes £300m in consequential loss payments, after sending out 17,000 redress determinations to customers.
Out of this amount, this equates to 14,000 included a cash redress offer while 3,000 determinations ruled that the interest rate hedging product "complied with [FCA] rules or that the customer suffered no loss."
In addition to the £1.5bn spent on redress, the banks have set aside money to cover the administrative costs determining whether customers' were mis-sold IRSAs.
Each case was analysed by the bank itself, alongside an independent reviewer.
"In 2012, we identified failings in the way that some banks sold IRHPs," said the FCA.
"The banks involved agreed to review their sales of IRHPs1 made to unsophisticated customers since 2001. The full review started in May 2013. Customer engagement in the review has been high with 89% of eligible customers choosing to have their cases reviewed.
"We remind customers who purchased caps that these sales will be included in the review only if they proactively complain. So far, 1,400 out of 7,400 customers have complained about caps. If you have purchased a cap product and wish to complain, we urge you to do it as soon as possible."