Shell's takeover of BG completed this week, launching a company to rival ExxonMobil in the Ultramajors league. Although we think that the tie-up has strong industrial logic and was done on fair terms, the macro environment has weakened substantially since the deal was announced in April 2015. Oil prices have halved, the 'lower for longer' scenario is now reality, and sentiment around the long-term is increasingly bearish. Against this background, the market re-rating that Shell was hoping to drive through the acquisition of BG has yet to materialise and the company trades at a 45% discount to our base case valuation. Making a success of the BG deal will be critical to unwinding this discount. Shell will need to demonstrate – through operational out-performance and delivery on shareholder returns – that the deal was done for the right reasons, at the right price, at the right time. We have identified five areas that will either make-or-break the success of the BG takeover for Shell.