Well...kinda. I don't know if they were invented for this specific purpose, but preferential shares do prevent activist shareholders from imposing their will on public companies, forcing them to take actions that are very short term. Preferential shares actually prevent that from happening, which is great.

This is a new dimension in that struggle. I don't know how this will pan out...

One thing I don't understand is why don't index funds take preferential shares into account when deciding which ones to buy/sell? Couldn't that be factored into the decision engine's rules/algorithms?