Marathon Petroleum Corp. and Andeavor said the waiting period under the Hart-Scott-Rodino Act expired, bringing the $23.3 billion merger between the two companies closer to completion.

Under the merger deal, Marathon would acquire all of Andeavor's outstanding shares, resulting in a combined company that is the top U.S. refiner by capacity.

Marathon and Andeavor also obtained regulatory clearance for the merger from the Canadian Commissioner of Competition, according to a July 3 news release. The deal awaits approval from Marathon and Andeavor shareholders and is scheduled to close in the second half of 2018.