Musk takes the Tesla-effect to Twitter?

I genuinely thought this was an April Fools Day story that I'd missed until now, but apparently Elon now has a 9.2% stake in Twitter and the news of this has Twitter's stock up 20%!

I don't know anything about how this works, but would owning so much of the company's shares give him sway over Twitter's policies? I suppose he'd have to be on the board or something, but he's had no shortage of criticism over the way Twitter has handled free speech issues.

It'll be interesting to see what comes of this!