Gupta-owned Oakbay Investments has questioned the timing of Finance Minister Pravin Gordhan’s legal .
The report, "Understanding Africa's Middle Class" found there were 15 million middle-class households in 11 of sub-Saharan Africa's top economies in 2014, up from 4.6m in 2000 and 2.4m in 1990.
This was an increase of 230 percent over 14 years.
Standard Bank political economist Simon Freemantle said the 11 economies in the study were Angola, Ethiopia, Ghana, Kenya, Mozambique, Nigeria, South Sudan, Sudan, Tanzania, Uganda, and Zambia.
The report found the combined gross domestic products of the 11 economies had grown tenfold since 2000.
"Looking ahead, an even greater elevation in income growth is anticipated in the next 15 years between 2014 and 2030. We expect an additional 14 million middle-class households will be added across the 11 focal countries, tripling the current number," Freemantle said.
He said income discrepancies were vast among the 11 economies. Eighty-six percent of the total number of households across these economies remained within the broadly low income band.
This was expected to fall to around 75 percent by 2030.