Gumede's lawyers plan to serve the summons on the newspaper after it said the SIU was investigating a tender awarded to his IT firm, Gijima.
Businessman Robert Gumede's legal team plans to serve a summons on the Sunday Independent soon, his lawyers said on his behalf on Saturday.
"[The legal team] are quantifying the damage to his reputation and the irreparable losses suffered by his companies, which operate globally, as a result of the defamatory article, which damages will exceed R1-billion," Brian Kahn Inc said.
Earlier this month, Gumede threatened to sue the newspaper, deputy editor Japhet Ncube, and reporter Mogomotsi Magome over an article published on March 2 under the headline "ANC funder probed".
The report claimed that Gumede's JSE-listed IT firm, Gijima, was the subject of an investigation authorised by President Jacob Zuma.
The report alleged that Zuma signed a proclamation for the Special Investigating Unit (SIU) to probe the R360-million tender awarded by the rural development department to Gumede's company. – Sapa.