The U.S. Justice Department will file a lawsuit as soon as this week to stop oilfield services provider Halliburton Co from acquiring smaller rival Baker Hughes, a deal that would combine the No. 2 and No. 3 oil services companies, a source familiar with the matter said. Share prices for Baker Hughes were down 6 percent at $38.99 at midafternoon Tuesday while Halliburton was up about 1 percent at $34.34. The two sides had been discussing asset sales aimed at saving the deal, which was announced in November 2014. In January, Halliburton told regulators it was prepared to sell assets with combined 2013 revenue of $5.2 billion. Halliburton and Baker Hughes both declined comment on Tuesday. If the deal collapses due to antitrust concerns, Halliburton must pay Baker Hughes a $3.5 billion breakup fee, […]