Q. The last few years I have included in my chometz sale, the stocks I own from corporations that deal with chometz.
I own some McDonald’s shares also and I sell them before Pesach. What about the basar vechalav stock (cheeseburgers), which is prohibited behanoah during the whole year, can I own them?

A. Poskim disagree in regards to owning shares in companies that trade and have possession of chometz products during Pesach. Some are lenient since the chometz goods are out of bounds for shareholders and they can’t take possession or sell it if they wanted to. This is akin to accepting responsibility over the chometz of a Gentile that is located on the property of the Gentile and is therefore permitted. (Mishna Berurah 440: 7)

Besides they don’t own the warehouses and have no right of access to it (Cheshev Hoefod 1: 82, Maharia Halevy 2: 124, Haelef Lecha Shlomo 238). Some Poskim are stringent and consider this type of partial ownership enough to transgress on the chometz prohibitions (Minchas Yitzchok 3: 1, Moadim Uzmanim 3:269). Today many Rabbonim include shares if owned in their sale document. (Piskey Teshuvos 440: 1)

Horav Shlomo Miller Shlit’a pointed out that there is a general tendency to be lenient in regards to bassar vechalav, since the proscription is less severe. In addition there may not be a prohibition of benefit at all on Tzli or fried meat and milk (see Yalkut Yosef 87 and Noam Halocho p. 31 quoting Maharam Shiff, Chavas Daas and others that there is no Hana’a prohibition). Another reason for leniency is the Rambam opinion that on bassar vechalav of an animal that is a nevelah there is no benefit prohibition (Rambam – Ma’acholos Asuros 9: 7, Lechem Mishma ibid.)

Rabbi A. Bartfeld as revised by Horav Shlomo Miller Shlit”a