Leading private-equity firms are highlighting their transformation into investors in deeply discounted debt as they purchase more leveraged buy-out financing from banks.

In the most recent deal, Royal Bank of Scotland is selling to Apollo, GSO Capital, Blackstone’s debt investing arm, and TPG as much as $8bn (£4.2bn) in loans that financed acquisitions by private-equity firms, people familiar with deal said. RBS did not respond to requests for comment.