Shares of of BG Group rose by as much as 42 percent before closing 27 percent higher and Shell slipped by over 5 percent.
"In the interim, Shell is taking on more risk and in issuing more shares and also in paying out cash to BG shareholders. As a result their balance sheet will become more stretched. And this potentially puts some strain on this dividend as they redirect cashflows to paying down debt ahead of growing the dividend," Matthew Beesley, head of global equities at Henderson Global Investors, said in a research note.
U.S. stocks gave back early gains to trade near the flat-line on Wednesday, as investors digested energy sector news and awaited the Federal Reserve's meeting minutes.
The key report for the day is the 2 p.m. ET publication of the Federal Open Market Committee minutes of the March meeting, when the Fed dropped "patient" from its statement as an indication it is setting up for normalization of monetary policy.
However, the overall tone of the minutes is expected to remain dovish.
Greece in focus
Greek Prime Minister Alexis Tsipras was in Moscow to meet Russian President Vladimir Putin on Wednesday. The meeting comes as both leaders face increasing isolation in Europe – Tsipras for his country's economic crisis and Putin for his country's annexation of Crimea and part in the conflict in east Ukraine.
Speculation has mounted that Russia could offer Greece financial aid but officials in Europe are worried any aid offer could be used to secure a Greek veto against any new European sanctions on Russia.
Putin said on Wednesday that Tsipras had not asked for financial aid, but that Russia could provide credit for joint projects in the future.
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