[acqq]

I can imagine that, still, how come "Goldman's" with the 's?

https://en.wikipedia.org/wiki/Goldman_Sachs

It isn't:

https://en.wikipedia.org/wiki/McDonald%27s

[scrumper]

Likely British usage. We pluralize company names in many cases: Goldmans, Tescos, etc, and refer to them plurally (so, "Goldmans are seeking to ruin Sergey" vs. "Goldman is seeking..."). Apostrophe is probably wrong :)

[acqq]

So would a Briton say "I used to work at Goldmans" if the company is called Goldman Sachs?

[scrumper]

Yes, exactly. Same with Lehmans, Merrills, etc. Mostly companies named after people.

[pests]

In southeast Michigan its also standard for people to append an `s` to the end of most stores.

Kroger -> Krogers Meijer -> Meijers

etc. I never noticed it until I went on a linguistics bender on Wikipedia where it was noted.