That's unbelievable, and yet, entirely believable. Wow. I'm sorry he was a part of that, and I'm glad he got out. It's such a nasty, awful industry. I've done some report generation stuff for banks (way before they called it data science) and it was strange being around people who were so highly strung and odd. I mean, there's parts of their personalities that just gave off "I could snap any moment" vibes.
Anyhow. Yeah. Finance sucks. They ought to make it illegal to work more than 40hrs in that industry, right away.
My uncle worked backend systems for a trading floor in the 90s. His last straw was when a vendor CE died in the datacenter, iirc of a heart attack during an early morning repair. Someone called 911 when he was discovered, but the fire/ems guys got into a fight with the management and security and stormed off.
They ended up getting threatened to complete the repair or get fired and rolled the dude into a cold corner of the datacenter, where he sat for several hours.