Five epic Wall Street fights

On Wall Street, traders work hard, play hard — and fight hard. At a certain point, I developed my own motto: If you screw me, I'll screw you harder.

Tired of being screamed at daily and living in fear of being fired, I finally left the Galleon Group in 2001 to help a co-worker start the hedge fund Argus Partners. Not surprisingly, one of my former bosses tried to put every single road block he possibly could in front of us to impede the launch of our new fund. He called every sales trader I know and told them if they do business with me, they can't do business with Galleon.

Financially, the guy could crush me, so I couldn't fight money with money. I knew the best way to inflict pain was by sending ego-bruising scud missiles. Argus Partners was a health-care hedge fund, but sometimes I got a fast call in other sectors. Like really fast. So occasionally, I'd send an instant message over to my former boss letting him know, for example, that Goldman Sachs (GS) was about to upgrade the semiconductor space in five minutes. And about six minutes later I'd get a call from my Goldman Sachs sales trader telling me the guy who covers Galleon just got DESTROYED over the phone.

They don't teach you that in business school. But if you work on Wall Street for more than five minutes, you'll learn how to fight bare-knuckled.

Here are five epic Wall Street fights and how they played out:

After a long battle over insider-trading allegations, Steve Cohen and his former hedge fund settled with the SEC by writing a check for more than $600 million. I'm sure the government considered it a victory. But two weeks later, Cohen wrote another check for more than $150 million to purchase Picasso's "Le Reve" ("The Dream"), one of the world's most expensive pieces of art, from casino mogul Steve Wynn. A day later, he shelled out $60 million for an oceanfront home in the Hamptons just down the road from one he already owned. Cohen apparently tried to keep the Picasso purchase on the down low, and wasn't in control of the timing of the sale, but you couldn't help but take his spending as a snub to the government that a $600 million fine meant very little to a man whose net worth is an estimated $11.4 billion, according to Forbes 2015 richest list.

Wall Street traders don't like to lose. A former co-worker of mine told me a story about a head trader and his No. 2 who were bickering over a $25,000 bonus. The No. 2 said he was entitled to a "performance bonus," given the fund's performance for the year. But the head trader said that, after the management fee was factored in, No. 2 didn't reach his goal. They went back and forth for weeks until the head trader finally agreed to give him the bonus. But, the head trader got in one last dig: He had the $25,000 bonus delivered to the trader's desk all in pennies — unrolled.

A sales trader friend of mine told me a story about a banker-turned-hedge-fund manager, who hired his former nemesis to be an analyst at his shop. It sounds crazy, but wait for it: He fired him on Day 364 – a day before annual bonuses were given out.

Wall Street is no stranger to divorce: Look around any trading desk there's at least two or three people going through a messy breakup at any given time. But one of the most explosive marital blowouts in recent memory has got to be Jefferies executive Sage Kelly and his wife Christina Di Mauro.

The allegations, which ranged from Sage's annual "Mushroom Day" at his home in the Hamptons to a four-person orgy involving a client and his girlfriend at the Ritz in Boston and questionable parenting skills, played out in the international media over the course of several months. They ultimately settled for an undisclosed sum (she had initially filed for $7 million), but the fallout went much further than their bank account: Kelly wound up stepping down from his post at Jefferies, at least two biotech stocks took a hit amid allegations of involvement by their CEOs and several Jefferies executives had to get urine tests.

One of the most infamous Wall Street feuds was between hedge-fund manager David Tepper and his former Goldman Sachs boss Jon Corzine. Tepper, who had apparently been passed over for partner, bought Corzine's beach house for $50 million – just so he could knock it down.

Burning bridges is frowned upon in most professions. But on Wall Street, we just call that Tuesday.

Commentary by Turney Duff, a former trader at the hedge fund Galleon Group. Duff chronicled the spectacular rise and fall of his career on Wall Street in the book, "The Buy Side," and is currently working on his second book, a Wall Street novel. He's also a consultant on the upcoming Showtime show, "Billions," starring Damian Lewis and Paul Giamatti. Follow him on Twitter @turneyduff.

Catch Turney Duff on the new season of CNBC's "Filthy Rich Guide," which starts Tuesday, Sept. 29 at 10pm ET/PT. Here's a sneak peek: