A former colleague of the arrested 'Flash Crash' trader said he 'had balls' in a presentation

Just last month, a former colleague of the arrested UK-based trader described him as "a legend" someone who "had balls" during the financial crisis, Bloomberg News pointed out.

On Tuesday, 36-year-old futures trader Navinder "Nav" Singh Sarao was arrested in London on charges in the US alleging that he contributed to the May 2010 "Flash Crash"-an event where the Dow Jones Industrial Average fell by approximately 600 points in a five-minute period, following a drop in the price of E-Mini S&P 500 futures contracts. Sarao was granted bail on Wednesday, and the US is seeking extradition.

Sarao's former coworker, Milto Savvidis, a prop trader at Futex Live, recently talked about him in his presentation to Kings College students. Savvidis said Sarao was considered a "legend" from his time at Futex.

Here's a quick excerpt from Savvidis' talk:

"This guy called Nav. He passed by the firm and he was there for, I don't know, maybe five, six years, he was a legend in our firm, we'd say."

"During the financial crisis, this guy, for lack of a better word, had balls. He just used to get into big positions, and he saw the risk, he saw the reward, and he took on the trades."

"And there was this one day where the market was just collapsing. Just literally, there was no end to it. It just kept going lower, and lower, and lower. He just stood in the way, put his bids in, bought up the market a few thousand lots, or whatever it was, and went home, went to sleep, came back the next day.

"The risk manager calls him up and tells him, you know, 'Nav, what's going on? This position, you want to get out of it?' He was like, 'Well, what's the status on it?' 'Well, up 13 million dollars' and he was like, 'Ok just get me out.'

"Now a normal person would be jumping for joy, going ecstatic. But that's part of his job. He just came in to do that. That's what he did. His goal was to take on the trade that made sense, not because he wanted the money, not because it was greed."

Bloomberg also reported that Futex's risk manager kept track of traders' profits and losses and that Sarao was always in the lead.

At the time of his arrest, Sarao was the sole employee of UK-based Nav Sarao Futures Limited. It appears that he traded his personal account from his home in a London suburb.

Watch below (start at the 5:45 minute mark):