S&P Global said late on Wednesday its BB/Stable/B rating on South Africa's Capitec Bank was not affected by a report from US research group Viceroy, which accused the financial house of reckless lending.

"Our ratings on the bank continue to reflect those on South Africa (foreign currency BB/Stable/B), as well as the bank’s strong capitalization and conservative reserving, which is appropriate for high normalized credit losses," S&P said.

"We also factor in the bank’s good earnings stability for a monoline unsecured consumer lender."

In its report, Viceroy Research urged the South African Reserve Bank to place Capitec under immediate curatorship, alleging that the value of its loan book was ‘massively overstated.’ 

Capitec's share price slumped over 20 percent on the JSE securities exchange on Tuesday, before recovering after the central bank issued a statement defending the soundness of the lender's capitalization and liquidity.