The City watchdog is expected to announce that thousands of small and medium sized businesses have been victims of a mis-selling scandal by Britain's high street banks.
The Financial Services Authority (FSA) announcement follows a Sky News investigation last year which exposed how companies were sold derivative products called swaps.
We discovered that complex financial structures had been sold to property developers, hotel owners, farmers, chip shops, butchers and even a kennel owner.
Swaps were marketed as protection for businesses against upward trends in interest rates, but claimants say they were not made aware of significant costs attached if rates fell.
While the banks profited from these agreements, thousands of companies have found themselves facing huge fees associated with the swaps and enormous breakage costs if they want to get out of the deals. Conversely, some agreements allow banks to pull out if rates rise.
Last August, a former swaps seller James Ducker told Sky News: "The way it was described once by one of my managers was, 'We give the customer an umbrella and when it starts raining we take it away.' Perfect, if rates go up, bank wins, if rates go down, bank wins."
One loser in this game was David Smith. He had been in the hotel business for over 35 years and believes he would still own the Grade II listed Westover hotel on the south coast, if his bank had not managed to get his signature on a piece of paper.
Mr Smith told Sky News: "The emphasis was on the fact that it was free anyway. Why should I worry about a free product that's going to protect me?"
His wife Christine added: "There were several phone calls to ask why we hadn't returned the paperwork and David didn't really want to sign it, but we decided that we had no option.
"We had a loan with the bank and we would do what the bank was advising us to do. I trusted the bank, I trusted them."
A report by a hedging expert shows the bank made thousands from the deal while David and Christine Smith ultimately lost their business.
The FSA has been investigating swaps and will formally announce where they are are up to at 7am on Friday - and Sky News has learned the FSA has uncovered evidence of banks mis-selling interest rate swaps.
Compensation measures are likely to be put in place and the banks will have to write to thousands of customers who have been affected.
There have already been attempted legal actions against the banks and several of them have settled out of court.
In December 2011, a couple who owned chip shop in Leeds took on HSBC (LSE: HSBA.L - news) , and the secretive settlement was estimated at around £200,000 in the chippy's favour.
Another case involving amounts around the £15m mark was also settled between Lloyds and a care home company called Wingate Associates. The company said it was satisfied with the agreement but has since made a claim against another bank for £36m.
Abhishek Sachdev, managing director of hedging advice firm Vedanta Hedging said: "Bank clients were not given a true picture of the downsides and the risks. They had an unbalanced view of the product. In the worst cases hedges were bigger and longer than the loans."
Mr Sachdev, who is FSA authorised, added: "Hedging is a useful tool when used as part of a careful, considered risk management strategy.
"However, banks take advantage of clients who do not understand pricing and underlying complexities of these products."
Comments from the banks are expected to be released after the FSA announcement.