South African president Jacob Zuma’s sacking of his finance minister Pravin Gordhan late last night saw a five percent drop in the value of the rand, the country’s currency.

South Africa’s deputy president Cyril Ramaphosa, a frontrunner to replace Zuma as African National Congress (ANC) president, described the decision as “totally unacceptable”.

Bank shares on the Johannesburg Stock Exchange plummeted 4.5 percent.

The FTSE/JSE Africa Banks Index slid as much as 7.7 percent on Friday, its biggest one-day drop since December 2015 — the last time Zuma sacked his finance minister.

The cabinet changes will leave South Africa’s credit rating vulnerable.

Zuma also dismissed eight of his other cabinet members and six deputies.

“I have decided to make changes to the national executive in order to improve efficiency and effectiveness,” he said.

However, the major cabinet overhaul — the biggest of its kind since the early 1990s — has been viewed as an excuse for the South African leader to silence his critics.

Gordhan’s insistence on fiscal discipline and his efforts to tame inflation were at odds with Zuma’s plans.

Gordhan was appointed in December 2015 to restore stability after Zuma abruptly replaced the then finance minister Nhlanhla Nene with a little-known backbencher.

“Unlike when Nene was fired, the opposition to Zuma within his government is now much stronger, presaging a full-blown political crisis,” said Nicholas Spiro, a partner at London-based Lauressa Advisory Ltd., which advises asset managers.

Zuma is due to step down as head of the party in December, before the 2019 general election.