​Payments processor Worldpay Group has priced its initial offer at 240p per ordinary share - almost exactly in the middle of expectations - meaning the company will have a market cap of £4.8bn when it goes public.  This makes it the biggest float this year, easily besting Auto Trader, which went public in March with a valuation of £2.3bn.  Private equity owners Bain Capital and Advent International had looking at an offer of between 225p to 260p, though this was narrowed on Friday to between 235p to 250p.  The offer is expected to raise total gross proceeds of approximately...