Marathon Petroleum Corporation has announced that it will be selling its Speedway gas stations to 7-Eleven.

Marathon says the $21 billion all-cash deal establishes a relationship with 7-Eleven anchored by long-term fuel supply agreements for approximately 7.7 billion gallons per year with additional growth opportunities also possible.

“This transaction marks a milestone on the strategic priorities we outlined earlier this year,” said Michael J. Hennigan, president and chief executive officer.

“Our announcement crystalizes the significant value of the Speedway business, creates certainty around value realization and delivers on our commitment to unlock the value of our assets. At the same time, the establishment of a long-term strategic relationship with 7-Eleven creates opportunities to improve our commercial performance.”

7-Eleven is a wholly owned, indirect subsidiary of Japanese retail company Seven & i Holdings.

There are nearly 4,000 Speedway gas stations in 36 states.