"South Africa has 811 830 stokvels [group savings clubs providing for mutual financial assistance, as well as social and entertainment needs] with a total estimated value of R44-billion (US$5.3-billion) according to a survey released on 21November.
“The value of the stokvel market would create a bigger sector than the
agriculture or electricity sectors,” said Mamapudi Nkgadima, managing director of African Response, in a statement.
"A nationwide survey by research company African Response found there were 11.4 million stokvel members in South Africa. “To put this in perspective, the population of a city made up of all the stokvel members
would be larger than any of our major metros, including Johannesburg, Pretoria, Cape Town and Durban,” said Nkgadima. The most popular type of stokvel is for savings, with 47% of respondents making use of this. It is followed by a burial society stokvel, of which 41% of respondents are members. Grocery stokvels, which buy in bulk from various retailers at the end of the year, make up 20% of stokvel membership. Investment stokvels make up 5% of the total stokvel market.
As big as this phenomenon is, the clubs themselves are pretty small:
"The survey found that the average number of members per stokvel was 27. “Burial societies tend to gather much higher membership numbers while investment and birthday stokvels are closer, more intimate
friendship groups.” Gauteng has the highest penetration of stokvels with 23%, followed by Limpopo at 20%. The majority of stokvel
members are women – at 57% . The exception is investment stokvels where men – at 52% – make up the majority. Of the stokvels, 66% had a bank account, while 34% were managed by members."
Source: http://thenewage.co.za/35734-1009-53- 
Implications from South Africa Horizon Scan:
"There is an innovation or social entrepreneurship opportunity waiting to
happen that could harness these ‘untapped’ savings of ordinary people – how and with what mechanisms / instruments is not patently clear yet. Perhaps something will emanate from that new Centre mentioned in
the preceding story."