To generate as much profit for their shareholders as possible.
Even that is not really their legal responsibility… if you’re thinking of their fiduciary duty, that means there is a responsibility to act in the best interests of the corporation & shareholders (rather than, eg, putting personal gain forefront). “Best interests” doesn’t necessarily mean “make the most money possible right now”, particularly if it can be argued that there would be long term damage to brand reputation etc by doing so.