It's Time To Break Up Facebook
“The cost of breaking up Facebook would be next to zero for the government, and lots of people stand to gain economically. A ban on short-term acquisitions would ensure that competitors, and the investors who take a bet on them, would have the space to flourish. Digital advertisers would suddenly have multiple companies vying for their dollars.”
There are parts of this piece that aren't great, but it lays out the historic precedent for getting rid of monopolies and talks about the way forward.