Shell announced that the combined group would cut up to 2,800 staff upon completion, or 3 per cent of the enlarged workforce, as it looks to secure one of the largest energy deals of recent years amid the oil price crash. Brent crude was trading at $37 on Monday.
Shares in BG fell 0.7 per cent on Monday to close at £9.20, and are about 10 per cent lower than the price outlined by Shell in its cash-and-stock bid, partly reflecting some concern that shareholders might not approve the deal.
The takeover requires the support of a majority of Shell shareholders and 75 per cent of those at BG.
One top-20 investor in Shell said: "The takeover price is far too expensive with oil trading at these levels. Investors should vote against it, but many probably won't."
A smaller investor in Shell and BG said the deal, at the current oil price, was "very expensive and makes less sense" compared to when there was hope of crude rising to $70 per barrel.
Another smaller investor said: "Companies always say they can make synergies out of these deals, but it is not clear that Shell can with BG, if the oil price remains low."