The Federation of Unions of South Africa announced in a statement on Friday evening that it has dismissed its general secretary Dennis George with immediate effect.
George’s dismissal follows his suspension from the trade union federation in late February over his shareholding in AYO Technology Solutions.
The statement did not say what wrongdoing George was accused of.
The IT company's funding by state-run asset manager the Public Investment Corporation has come under the spotlight at the judicial commission of inquiry into the PIC.
The commission is investigating allegations of wrongdoing at the asset manager, which manages R2.2trn in investments on behalf of public servants. The PIC invested R4.3bn in AYO in late 2017.
On Friday Fedusa said its National Executive Council had a meeting on Thursday where it considered recommendations by an independent chair of an investigation into AYO.
The council "unanimously resolved to dismiss George based on findings of serious misconduct," the statement said.