Is it permissible to sell food that Halacha forbids for consumption? If a person owns a variety store, for example, may he sell food items that are forbidden to be eaten?
The Shulhan Aruch addresses this question in the Yoreh Dei'a section (117:1) and rules that one may not sell non-kosher food items on a regular basis, such as in the aforementioned case of selling non-kosher food as regular merchandise in one's store. One may, however, sell non-kosher food on an occasional basis; for example, Jewish slaughterhouses may sell the meat of animals that are discovered to be unfit for consumption. Since these sales are not part of the slaughterhouses' ongoing business operations, they are permissible.
The Shach (commentary to the Shulhan Aruch by Rabbi Shabtai Ha'kohen, 1621-1663) explains that although the Torah explicitly permits selling non-kosher meat to gentiles (Devarim 14:21), the Sages enacted a prohibition forbidding the trade of non-kosher food. Some attribute this enactment to the concern that one who sells non-kosher food on a regular basis might eventually partake of it, while others explain this law on the basis of "Mar'it Ha'ayin," the concern that people might wrongly suspect such a person of eating non-kosher food.
The Shulhan Aruch adds that just as Halacha forbids doing commerce with non-kosher food, so may one not be a partner in a company that trades in non-kosher food products. This Halacha gives rise to the question concerning owning stock in non-kosher food chains, such as McDonalds. Does shareholding in a company constitute a "partnership" with respect to this Halacha, or might we somehow distinguish between shareholders and partners?
Rabbi Moshe Feinstein (Russia-New York, 1895-1986), in his Iggerot Moshe (Even Ha'ezer 1:7), rules that one may own shares of stock in a non-kosher food chain provided that he does not exert any decision-making control in the company. Even if shareholders are a given a vote on company decisions, shareholders are not considered "partners" with respect to this Halacha and thus may own stocks even though the company trades in non-kosher foods. If, however, somebody owns over 50% of the company and thus has a say in the company's operational decisions, he is considered a partner and may not continue owning the stock if the company deals in non-kosher food products.
This entire discussion relates only to foods that are forbidden by consumption on the level of Torah law. Foods that are forbidden by force of Rabbinic enactment, however, may be sold by Jews without any restrictions, even as a permanent business arrangement. In all situations, then, one must consult with a competent Halachic authority to determine the status of the food in question.
Summary: Halacha permits selling non-kosher without restriction if the food is forbidden only by force of Rabbinic enactment. Food forbidden on the level of Torah law, by contrast, may be sold only on an occasional basis, but not as part of an established commercial enterprise. Likewise, one may not enter into a partnership in a company that trades in foods forbidden by Torah law. One may own stock in a non-kosher food company provided that he does not enjoy any decision-making control in the company.
See the book- "Pure Money" by Dayan Cohen, pages 191-192.