When Marathon Petroleum (MPC - Get Report) announced in October that it was planning to drop its midstream business into its master limited partnership, MPLX LP (MPLX - Get Report) , over three years, the move was taken partly in response to a behind-the-scenes effort by activist investment fund Elliott Management. But it wasn't enough.

Marathon Petroleum began planning for such a transaction, according to people familiar with the situation, but Elliott, managed by billionaire Paul Singer, didn't believe the effort was moving fast enough. The activist fund began engaging with Marathon Petroleum in September, roughly a month before the announcement was made, they said. But when Marathon Petroleum released its plan, Elliott didn't believe the energy company was doing enough. Elliott wanted Marathon Petroleum to also consider strategic options, such as a sale or spinoff, for its gasoline station and convenience store operations, Speedway LLC unit, the people familiar with the situation added.

As a result, the activist fund took their campaign public. In November, Elliott launched a public campaign seeking to have Marathon Petroleum expedite the shift in assets to the master limited partnership and consider a full strategic review over whether a tax-free separation of the company into three businesses would best serve shareholders over the long-term.

As negotiations continued, Marathon Petroleum in December postponed the deadline for shareholders (Read: Elliott) to nominate dissident directors until January 9. However, shortly before that deadline, on Jan. 3, Marathon Petroleum announced a new expedited plan that Elliott approved of. It would start the new year with a strategic review of its Speedway division, and accelerate its dropdown sale to MPLX. Marathon said it expects that a drop down of $1.4 billion in midstream's assets to MLPX will be completed in 2017.

With the announcement, Elliott will be in wait and watch mode. Marathon Petroleum hired Goldman Sachs (GS - Get Report)  and Evercore Partners. to assist it on its strategic options for MPLX, according to people familiar with the company. However, no announcement has yet been made about what investment bank Marathon Petroleum has hired to consider strategic options for the Speedway unit. Marathon Petroleum has said it plans to provide an update on the strategic options by mid-2017 on the Speedway review.

And even though Elliott approved of the plan expect Singer to be keeping a watchful eye on its execution. Selling the Speedway unit would be somewhat of an about-face to Marathon's recent strategy after it spent $2.9 billion less than two years ago to nearly double the size of the operation by acquiring the gas station segment of Hess Corp. (HES - Get Report) .

The deadline has passed for Elliott to launch a director-election battle at Marathon Petroleum's 2017 annual meeting. However, considering that Elliott is not shy when it comes to nominating director candidates, and the fact that at least one other activist has a stake in the company, Jana Partners' Barry Rosenstein, a failure to consummate a sale or spinoff of the Speedway business, for example, could result in a proxy contest at the company's 2018 annual meeting. Marathon Petroleum declined to comment.