Takashi Kotegawa (BNF): The Japanese Trader Who Made Billions — and Why Almost Nobody Can Copy Him

The man behind BNF

Takashi Kotegawa was born in 1978 in Ichikawa, in Chiba prefecture near Tokyo. While still a university student, in 2000, he began trading Japanese shares online with about ¥1.6 million saved from part-time jobs. He posted on Japanese internet forums under the name BNF, inspired by the American trader Victor Niederhoffer. Within a few years his results had made him a legend among Japan’s retail traders, although he gave very few interviews and has always kept a low profile.

The J-Com trade

On 8 December 2005, the first day of trading in the recruitment company J-Com, a Mizuho Securities employee entered an order to sell 610,000 shares at ¥1 each instead of one share at ¥610,000. The order was many times larger than the number of shares J-Com had issued, and the market went into chaos. Kotegawa was one of the traders who bought: he acquired 7,100 shares and, after the error was unwound, reported a profit of more than ¥2 billion — then about $17 million. He was 27 and, as the newspapers noted, technically unemployed. Mizuho’s loss from the mistake was about ¥40.5 billion.

How he traded

Kotegawa traded mostly short term. By most accounts he looked for shares that had fallen sharply and unusually far below their recent average price, bought into the panic and sold within days when prices recovered. He followed the market for most of the day, reacted quickly to news and cut losing positions fast. He has said little about his methods in public, so much of what is written about his “strategy” online is reconstruction rather than his own account.

His fortune was reported at around ¥19 billion in 2008, and in October that year he bought a commercial building opposite Akihabara station in Tokyo for about ¥9 billion. He reportedly turned down offers to manage other people’s money and continued to trade his own.

For every Kotegawa there are thousands of traders nobody writes about, because they lost.

Why his story misleads

Kotegawa’s record is real, but it is a poor guide to what will happen to anyone who tries the same thing. We hear about him precisely because he is exceptional; the many people who started trading at the same time and lost their savings do not get articles written about them. This is survivorship bias, and the data on day trading show how strong it is. A study of everyone who began day trading index futures in Brazil between 2013 and 2015 found that, among those who kept going for more than 300 days, 97% lost money, and only 1.1% earned more than the minimum wage. Research on Taiwan, where detailed records exist, found that fewer than 1% of day traders could reliably earn returns above the market after fees.

What investors can take from him

• Extraordinary results attract attention; the odds are found in the averages, not in the stories.
• Speed, discipline and cutting losses fast are necessary for short-term trading — and still not enough for most people.
• The J-Com profit came from someone else’s mistake in a market that is not normally that generous.
• Trading full time is a job: Kotegawa reportedly spent most of every trading day watching the market, which few people with other work could match.
• For building wealth, time in the market and low costs have a far better record than frequent trading.

If his story makes you curious about trading, start with the evidence. For long-term savings, a diversified, low-cost portfolio held for years remains the approach with the best odds for ordinary investors. This profile is general education, not investment advice.

This article is educational and general in nature. It isn’t personalized investment, tax, or legal advice — always weigh your own circumstances, or talk to a licensed professional, before making financial decisions.

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