Matt Levine is the author of regular column "Money Stuff" on Bloomberg, and he seems to have spotted a paperclip maximizer in the wild:

A key explanation of, like, modern life is that politics are so vicious and polarized because (1) everyone uses Facebook, (2) Facebook has an algorithm to decide what stuff to show people, (3) that algorithm is built to maximize engagement, (4) the algorithm is very effective, and (5) it turns out that what maximizes engagement is vicious polarizing stuff, oops. That probably exaggerates the role of Facebook’s algorithm and understates the agency of its users — “Everything you hate about the Internet is actually everything you hate about people,” says Balk’s First Law — but there’s something to it. Social media reflects and also shapes human behavior, in an emergent way. It targets a behavior it likes — spending more time on Facebook, basically — and tries to maximize it. To do that, it maximizes behaviors that correlate with the target behavior, like posting and reading vicious political content. It gives people what they want, as revealed by their actions, which is not what they actually want. (Or is it?) And so at some level you have behaviors in the real world that seem to be designed by an algorithm to maximize engagement on social media; politics are vicious and volatile because that’s what Facebook, deep down, wants.

Okay now let’s do stocks! At Margins, Ranjan Roy has a great post on “Memestocks and Reddit redesigns” arguing that some of the 2021 meme-stock craze is due to changes in Reddit’s algorithms to maximize engagement: The stock market is volatile and bizarre because that’s what Reddit, deep down, wants. You read about a stock, Reddit sends you “you might also like ...” notifications about that stock and other stocks, those notifications are designed to draw you in, they work, you spend more time looking at stocks on Reddit, your identity starts to become “person who cares about this stock,” you buy the stock, you start posting about it, you start buying weekly-expiry out-of-the-money call options on the stock and posting your daily profits and losses, the stock goes to $1,000, it becomes the biggest story in the national news, everyone in the country is obsessed with it, and they are all coming to Reddit because the story is not “stock goes up” but “stock goes up because people are having fun and getting rich on Reddit.”

From the dumb perspective of the Reddit algorithm that sends you those notifications, this is what success looks like: It sent you those notifications, and now everyone is on Reddit. It is a paperclip maximizer: Its goal is to get more people to spend more time on Reddit, and the way it does that is to cause global financial markets to be wildly volatile and disconnected from fundamental value because it turns out — who knew? — that that drives more engagement with Reddit. Nobody at Reddit sat down and said “hey we should pump up some weird stocks, that will maximize traffic”; its engagement algorithms just figured that out on their own. And now here we are.

Source is https://www.bloomberg.com/opinion/articles/2021-09-23/dark-pool-sold-some-order-flow and randomly (? I don't understand the algorithm or criteria), you sometimes get a paywall when you visit that link and sometimes you don't.