Monday was a dark day for many investors, but a Japanese man who goes by the Internet handle CIS won big.

The day trader made a big bet against the market and came away with $34 million, talking his 40,000 Twitter followers through the extraordinary developments in a series of tweets, write Jason Clenfield and Yuji Nakamura for Bloomberg.

Twitter

Day traders holds his nerve to nearly triple profits

Many investors were paralyzed by market instability this week, but not CIS. “I do my best work when other people are panicking,” he said in an interview Tuesday.

He spoke on condition of anonymity, expressing worries about robbery or extortion. CIS backed up his claims with online brokerage statements showing how his blockbuster trades developed.

Since mid-August, CIS had been shorting futures on the Nikkei 225 Stock Average. On Monday he could have walked away with $13 million, but he kept trading. By the close of the day in New York, those profits had doubled, but still he kept trading, betting that the market had bottomed.

Twitter-trader

By Tuesday, when he finally cashed out, he claimed to have almost tripled his profit.

Anonymous trader enjoys cult following on Twitter

CIS has become something of a celebrity among Japanese day traders, and was profiled in the Bloomberg Markets magazine last year. He claimed to have a personal fortune of around $150 million which he had amassed mostly from day trading from a spare bedroom in a rented apartment.

Now 36, CIS made a name for himself for his brazen trash talk on Internet message boards for day traders, occasionally uttering such immortal lines as “Not even Goldman Sachs can beat me in a trade.” In 2014 he opened a Twitter account, which he uses to talk about video games and trading.

He met the Bloomberg interviewers at a Tokyo coffee shop clutching a $1,600 bottle of wine, but quickly told them that he suffers losses as well as successes. The crisis in Greece reportedly cost him $6 million.

His overall philosophy is to “buy stocks that are being bought, and sell stocks that are being sold,” and he pays little attention to the global economy. the latest blockbuster trade was extremely high stakes, shorting 1,500 contracts at around $160,000. He bet against the Nikkei to the tune of $240 million, and would make or lose $1.25 million for every 100 yen move in the index.

CIS tells Twitter how he profited from investor panic

The market dipped on Friday, and plunged on Monday, with futures falling over 1,000 points. CIS stood to make $13 million. Instead of cashing out, he sold 200 more contracts, raising his bet against the Nikkei to around $275 million and banking that fear around the U.S. open would drive Nikkei 225 futures down even further.

As the Dow Jones Industrial Average fell over 6%, the Nikkei fell again and CIS cashed out his position for a $27 million profit. He then saw an opportunity to make money from investors looking to protect themselves from a further fall in the Nikkei.

Betting that the market had bottomed out, he started buying futures. By 1 a.m. Tuesday he had amassed 970 contracts, a $145 million bet that the market would rebound. In the morning, Nikkei futures stood around 18,000 and recovered slowly before CIS closed his position in the afternoon.

Although he won big this time, do not be tempted to blindly follow CIS trading patterns on Twitter. “When a trade goes right I feel like bragging a little, but I don’t get on Twitter to talk about it if I lose,” he said.