Speculation over cabinet changes began when Zuma called a meeting of the ruling African National Congress' top officials on Thursday evening.



"I have directed the new ministers and deputy ministers to work tirelessly with their colleagues to bring about radical socioeconomic transformation and to ensure that the promise of a better life for the poor and the working class becomes a reality," Zuma said.



Earlier, the ANC-allied Communist Party (SACP) said Zuma had told its officials on Monday that he planned to sack Gordhan. The SACP said it had objected, while the main opposition said it would call a vote of no-confidence in Zuma over the matter.



For the second consecutive day, the influential ANC Youth League issued a statement on Thursday backing Zuma's planned cabinet changes.



Local assets have been under pressure since Monday, when Zuma ordered Gordhan to abandon an investor roadshow in Britain and fly home. Zuma gave no reason for the recall.



Gordhan said upon his arrival on Tuesday that he was still finance minister. On Wednesday, he said he would "open a new chapter" of his life if sacked.



Gordhan first served as finance minister from 2009 to 2014 and was brought back by Zuma in December 2015 to calm markets spooked by the president's decision to replace his respected successor, Nhlanhla Nene, with a little-known politician.



Opposition leader Mmusi Maimane, leader of the Democratic Alliance, urged resistance to Zuma's decision to fire Gordhan and Jonas. "We cannot sit by and let this happen," he said.



Unknown Gigaba



Gigaba was an unknown quantity, analysts said.



"The market will struggle to digest Gigaba. We think this is bad for the market and for SA," Nomura emerging markets analyst Peter Attard Montalto said in a note.



"We view this as an open attack on Treasury to replace people who are conservative and anti-corruption with people loyal to Zuma."



Some pundits say Gordhan is being pressured by a faction allied to Zuma, which has clashed with him over his plans to rein in government spending, the management of state enterprises and the running of the tax agency as the economy stagnates.



Africa's most industrialised economy faces the risk of being downgraded to junk status owing to weak economic growth after it got a reprieve last year. The economy grew by 0.3 percent in 2016 versus 1.3 percent in the previous year.



"The little that we know at the moment is that its probably not good news for the markets because he (Gigaba) doesn't have any real finance experience," said Noelani King Conradie, managing director at NKC African Economics.



"This definitely raises the risk of rating downgrades and it is going to continue the uncertainty about future economic policies."



Zuma shrugged off pressure from within his own party, the opposition as well as the business circles to keep Gordhan.



Two senior sources told Reuters on Thursday that Zuma was considering offering to step down next year, at least 12 months before his term ends, in a deal with his opponents in the party that would see Gordhan leave office now.



On Wednesday, sources within the ANC told Reuters there was a split down the middle among its six most senior officials over whether Gordhan should be sacked.



Julius Malema, leader of the ultra-left Economic Freedom Fighters (EFF) and a former protege of Zuma, filed a court application for disciplinary or impeachment proceedings against the president on Thursday.



Daniel Silke, a political analyst and director at Political Futures Consultancy said Zuma had taken a risk.



"This has been a long time coming. The president has clearly taken a politically risky decision to remove a finance minister who is well regarded both domestically and internationally," he said.