May I own stock in a company that sells non-kosher food, or one that sells chametz on Pesach?
Although companies like McDonald's sell non-kosher food, including meat and milk that is mixed together (from which it is prohibited to benefit) most halachic authorities maintain that it is permitted to own such stocks since you have no rights of ownership in the actual products; rather, you only have dividends from the company's investments. As for owning stocks during Passover in a company that makes chametz, since the stockholder has no right to do anything at the plant on his own accord, and certainly has no right to destroy the chametz, he is not in violation of owning chametz.

Note: Israel changes to "shaon kayitz," summer time early Friday morning, March 24.