Marathon Petroleum Corporation (MPC) is currently offering to buy back $4 billion USD of their stock (reference).
The minimum they will pay is $56, and the maximum is $63.
Given that this equity is currently trading at $63.61, why would someone want to do this?
Even if MPC was currently trading at only $63, why would it be appealing to sell it back to MPC instead of just trading it on the open market?