Punishing past behavior by a long chain like that seems extremely inefficient. Sure, if society could coordinate well enough to not fund bad behavior, that coul

Punishing past behavior by a long chain like that seems extremely inefficient. Sure, if society could coordinate well enough to not fund bad behavior, that could be a large enough effect to matter. But the optimal level on which to act seems to me to be the government level. If society doesn't want such companies, society should elect politicians etc that lead to them being banned. Note that boycotts are different. A boycott directly takes money away from the target that would have been spent otherwise. This takes money away from someone who didn't take money away from someone etc. So you can endorse private boycotts of products but not private boycotts of stock.