Treasury director general Dondo Mogajane told the judicial commission of inquiry into state capture that when Nhlanhla Nene was removed as finance minister in 2015, there was a reduction of about R378bn in market capitalisation on the JSE.
"Business confidence was at its lowest following Nene's removal," he told inquiry chairperson, Deputy Chief Justice Raymond Zondo on Friday.
At the time, Mogajane was the deputy director general for public finance at National Treasury.
"You say in paragraph 4 that there were serious adverse consequences flowing from the removal of Minister Nene and I'd like you to get there and explain to us in your own words what those consequences were," evidence leader advocate Vincent Maleka said to Mogajane.
Based on National Treasury's modelling of the micro economic impact of Nene's axing, Mogajane said: "There was indeed what I term [a] catastrophic fall of the rand at the time and the impact was that we saw about 148 000 jobs lost in terms of the model we ran. We saw a reduction of about R378bn in the JSE markets capitalisation. We also costed the impact of at least 1.1% of GDP by the end of ... 2017."
Mogajane said the period nominated for calculation of their model was from the announcement of Nene's exit, until his replacement, before the Asian market opened that Sunday.
He said the impact of Nene's removal could still be felt, even today.
"Can you, in National Treasury, confirm the extent of business and associated revenue the Gupta-owned entities received from government?" Maleka asked. "Can you model that revenue stream, especially in 2015?"
Mogajane said he would not be able to give the cost structures, but added that he had already requested staff to model the expected cost and revenue.
"I have asked our chief procurement office, together with our financial management office, to model the cost and the revenue that would have been accrued to the Gupta empire ... I will certainly make it available to the commission."
Nene was replaced by Des van Rooyen who in turn, was replaced by Pravin Gordhan (now public enterprises minister) just days later.