‘s newsletter. You can . Michael Sinkinson is a Count Chocula guy. Sure, it’s not the healthiest breakfast. But he finds what General Mills describes as “the chocolatey cereal with spooky-fun marshmallows” just delightful. Sinkinson is an (adult) economist at the Yale School of Management, and he says he’s been known to indulge himself in Count Chocula and other “Monster cereals” when they come out around Halloween. But lurking behind the Count Chocula box he’s been eating is a shadowy specter. It’s a potential problem for our economy known as “the common ownership hypothesis.” Over the last couple decades, investors have poured trillions and trillions of dollars into index funds and other massive funds run by three companies: Vanguard, BlackRock, and State Street Global Advisors, which together have over $16 trillion in assets under their control. If you have a retirement account, there’s a good chance it’s run by one of them. Their combined average stake in each of the biggest 500 American corporations (aka the S&P 500) went from 5.2% in 1998 to 20.5% in 2017. As we’ve written before in the