Private equity groups and hedge funds are among those buying the loan books, then hiring bankers for up to £2,000 per day to manage and restructure the portfolios.
Alternatively the managers are paid a share of the returns they make by restructuring the portfolios, which Interim Partners believes could give a higher income than the day rate.
Banks including Lloyds and RBS have been particularly active selling off portfolios. Private equity group Cerberus paid £860m for two corporate and commercial loan portfolios late last year.
Other examples of investment in the sector include KKR raising $2bn (£1.2bn) to invest in distressed debt, while Apollo has raised $3.9bn for European distressed assets since 2008.