HSBC has just weeks to come up with a concrete offer for a controlling stake in Nedbank, South Africa’s fourth-largest bank, in a deal that would leave the UK bank well placed to benefit from growing ties between Asia and Africa. HSBC on Monday entered into exclusive talks to buy 70 per cent of Nedbank’s shares, including a 52 per cent stake held by Old Mutual, the insurer. The UK bank now has about two months to come up with a firm offer. Richard Stovin-Bradford analyses the latest moves in the story he broke last Friday.