FinanceChevron and ExxonMobil raids open a 'new era of oil mega mergers', say analystsAnalysts and commentators say more M&A activity looks inevitableC-suite discussions: Hess chief executive John Hess (left), with Chevron chief executive Mike Wirth on the floor of the New York Stock Exchange on Monday.Photo: REUTERS/SCANPIXRussell SearanckeOslo