Not really a "blog" per se but Matt Levine's "Money Stuff" newsletter is frequently cross-posted on Hacker News (usually for columns about Tesla, WeWork, and Robinhood) but he's hands-down one of the best writers at the intersection of business and law/regulation. Once you learn about his themes re: "Everything Is Securities Fraud" and "Should Index Funds Be Illegal?" you will see it pop up in reality on a daily basis.
You can subscribe to his newsletter here: http://link.mail.bloombergbusiness.com/join/4wm/moneystuff-s...