If a company divests, it sells some of the things it owns — a factory, a smaller company, shares, land — so that it no longer holds them. The picture underneath is “taking the coat off”: the business is stripping itself of something it used to wear. This is a formal, newspaper-and-boardroom word, not what you say when you sell your bike to a friend. Activists also use it: if they ask a university to divest from oil, they mean sell those shares and stop putting money there. You may still meet the older, wider use divest yourself of — get rid of a title, a duty, or (rarely now) clothes. In company talk, though, it almost always means selling assets or pulling investment out.