Can a Jew own a non-kosher-food butchery that sells pig? And if he can, can he sell to non-practicing Jews?
Can a Jew own a non-kosher-food butchery that sells pig?
but maybe if he only owns stock in the butchery it is permitted since he does not own it in such a way that he has the right to eat from it
Shulchan Aruch YD 117.1
Anything that is specifically for eating and Biblically prohibited, even though it is not forbidden to derive benefit from it, is forbidden to do business in it.
Rambam Ma'achalot Assurot - Chapter 8:halacha 16
Whenever it is forbidden to partake of a substance, but it is permitted to benefit from it, even though it is permitted to benefit from it, it is forbidden do business with such articles or establish oneself in a profession that involves forbidden entities.[There is] an exception, forbidden fat, for concerning it, it is written: "You may use it for any task." For this reason, we do not do business with nevelot, trefot, teeming animals, and swarming animals.
from footnote there
The rationale for the prohibition is that we fear that a person who has extensive involvement with forbidden substances may come to partake of them (Rashba).
Aruch Hashulchan Y"D 117