Six weeks after Roche went hostile in its bid to buy out Genentech’s minority shareholders, the Swiss drugmaker and its longtime US partner have made up. After months of back and forth, Roche and Genentech’s board on Thursday agreed to an offer for the 44 per cent of the US biotechnology group that Roche does not yet own. To seal the deal, Roche added an extra $2 per share to an already-sweetened $93 per share offer it launched last week, which in turn followed an $86.5 bid pitched directly to shareholders in January.

Investors could be forgiven for wondering why it took the company so long to get to a $95 offer. After all, Genentech’s shares rose to $94 the day Roche launched its very first bid for control, which was a friendly $89 offer back in July. Rather than raise its initial bid, as Genentech shareholders hoped, Roche walked away. Ten months, one hostile approach and a 31 per cent slide in world pharmaceutical shares later, Roche is back where Genentech investors indicated it needed to be at the start.