FINDLAY, Ohio (AP) --€” Marathon Petroleum (NYSE:MPC) said Monday that it entered into a $500 million accelerated stock buyback program.

The accelerated stock buyback is the second tranche of share repurchases under a $2 billion stock buyback authorized by the company's board earlier this year.

The total number of shares to be repurchased will be based on the volume-weighted average price of Marathon stock during the repurchase period. Based on Marathon's Friday closing price of $53.05, the total shares to be bought under the accelerated program would represent about 2.8 percent of the company's outstanding shares.

The stock buybacks are expected to be completed before the end of the first quarter of 2013. The total value of the buybacks under the pair of accelerated repurchase programs put in place this year is about $1.35 billion, with $650 million remaining under the current authorization.

Findlay, Ohio-based Marathon Petroleum operates oil refineries and pipelines, and it sells fuel to drivers through its Speedway service stations. Its shares rose $1.71, or 3.2 percent, to close Monday trading at $54.76.

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