FRANKFURT (BLOOMBERG) - Billionaire activist investor Christopher Hohn has called on Wirecard to remove chief executive officer Markus Braun after an independent audit of past revenues criticized the German payments processor for internal "shortcomings."

The probe by KPMG was unable to obtain the data needed to verify revenues of 1 billion euros (S$1.54 billion) in transactions with third parties. Wirecard hired the accounting firm in October to look into its third-party partner business as well as operations in India and Singapore following a series of reports by the Financial Times that accused the company of accounting fraud in several countries.

Given management didn't provide KPMG with the necessary documentation to verify the revenue, "we are of the view that the supervisory board is legally obliged to intervene," Hohn's TCI Fund Management said in a letter also posted on its website.

"In our opinion, the necessary intervention is now to remove the CEO from all management duties," TCI said. Failing that, the board must take responsibility for the investigation and remove Wildcard's management from involvement in the audit until the allegations have been resolved, it said.

TCI has a short position in Wirecard, equivalent to 1.04 per cent of the company's stock.

Hohn's hedge fund, which managed about US$30 billion (S$42.5 billion) before suffering its steepest ever monthly decline in March, specializes in taking large stakes in companies and agitating for change to boost the firms' share prices.

His bets have included companies such as ABN Amro Bank, News Corp and most recently some attempted agitation against the London Stock Exchange Group.

The tactic has worked well for TCI - it's made money every year since 2008. It gained 41 per cent in 2019, its best annual performance in six years.