When it comes to mergers and acquisitions (M&A) in the oil & gas market, what a difference two years makes — let alone 20.

November 2014 saw Halliburton agree to buy Baker Hughes for around $34 billion, but fast forward 24 months and the suitors switched, with Baker Hughes now part of GE Oil & Gas following a recent $32 billion merger.

Halliburton’s move to rival industry giant Schlumberger was clobbered by US antitrust authorities, a fate Schlumberger escaped in its $14.8