[blep_]

Let's rephrase then: why does owning stock imply financially supporting the company? After IPO, you're not buying anything from the company, you're buying from other investors.

[azmodeus]

Stocks are also called shares, the name is a bit of a give away. It’s a share of a company you are a partial owner of it with some rights.

I think you do endorse the company whose shares you hold, in particular if it’s public knowledge.

[Fezzik]

Not only that, but your goal as a shareholder is to benefit financially from the company. If a company is a bad actor and you know it, you are expressly financing and benefitting from bad acts. I’m not sure why other commenters are trying to abstract this fact out of existence. It is not rocket science!