David Shapiro on Greenside High billionaires, Prosus, Comair, MTN and Mondi

South Africa's favourite market commentator is at his best when recalling connections from decades of growing up in Johannesburg and working at its world famous stock exchange. In this interview from the latest episode of Rational Radio, the Greenside High old boy shares his thoughts on a now famous former schoolfriend, Rodney Sacks, who founded the US's Monster Energy, a company worth $35bn. Sacks is in the SA news after resigning after decades on the board of Comair, which owns Kulula.com and operates the British Airways licence in Southern Africa. Shapiro also applies his mind to SA-owned Prosus's unsuccessful R100bn hostile takeover bid for the UK's JustEat; looks at MTN's good news from Nigeria and muses on the departure of the Mondi Group CEO after a relatively short stay at the SA-conceived multinational. - Alec Hogg