When he decided to place a buy order, how did he quickly calculate how much capital to commit? Was that the entirety of the available funds in his account at that time?

Sure, let's talk about B.N.F. (Takashi Oshikawa), the legendary Japanese retail investor. His fast, accurate, and formidable trading style truly captivates and intrigues many.

Unveiling the Fund Management of "Japan's Stock God" B.N.F.: Behind the Fast, Accurate, and Formidable Approach

When discussing B.N.F., many think of his astronomical profits. But his success stems not just from picking stocks correctly, but also from his highly distinctive approach to deploying capital. Let me break it down for you in plain language.

I. How did he "quickly calculate" how much money to invest?

First, understand that B.N.F.'s "calculation" is entirely different from the "precise calculation" most people imagine—the kind that involves punching numbers into a calculator for ages. His calculation was more like an instinctual response based on "opportunity certainty."

Think of it like an experienced hunter:

Spotting a small rabbit, he might casually take it down with a sling.
Seeing a wild boar, he immediately switches to his shotgun.
If he spots a dinosaur (a metaphor, of course), he might call for artillery support without hesitation, pouring all his "ammunition" into the strike.

This is how B.N.F.'s decision-making worked. The core of his "calculation" wasn't complex math formulas; it was answering a single question: "How much firepower does this opportunity in front of me deserve?"

His judgment was primarily based on these points:

Signal Strength of the Core Strategy: B.N.F. is most famous for his "buy-the-dip" strategy, specifically targeting stocks that experienced sharp short-term declines and deviated excessively from their 25-day moving average. This "degree of deviation" (Bias Rate) represented his "signal strength." The more extreme the deviation, the more severely he believed the stock was mispriced, increasing the probability and potential magnitude of a rebound. To him, this signaled a higher "certainty" opportunity. The stronger the signal, the more capital he deployed.
Simplify the Calculation, Prioritize Efficiency: For a short-term trader racing against the clock, time is money. He didn't bother with calculating Sharpe Ratios or the Kelly Criterion. His calculation could be incredibly straightforward: "I understand this opportunity perfectly, I'm supremely confident, so I'm putting in all the money I can!" Therefore, the calculation process might literally be Available Account Funds / Current Stock Price = Maximum Purchasable Shares.
Intuitive Feel and Experience: This part is the hardest to quantify but also the most important. Years of intensely scrutinizing the market gave him an almost instinctive understanding of market rhythms and individual stock behaviors. This "intuitive feel" would tell him whether the potential rebound was likely minor or significant, directly influencing his capital commitment.

So, his "rapid calculation" was fundamentally a process more qualitative than quantitative. He wasn't solving a math problem; he was "grading" the opportunity in front of him and then matching it with the appropriate amount of "firepower."

II. Did he invest all available funds in his account at that time?

The answer to this question is: On many crucial opportunities he identified, yes, he went almost all-in, deploying the vast majority or even all of his available capital—what we commonly call "All-in."

This is precisely where B.N.F. stands out as unique—and it's also the highest-risk aspect, something ordinary investors should not imitate.

Concentrated Investing, Not Diversified: Traditional investment wisdom warns, "Don't put all your eggs in one basket." B.N.F.'s philosophy was the opposite. He believed: "When you see it clearly, put all your eggs in that basket and guard it fiercely." Through his incredibly high win rate and heavy commitments on key opportunities, he achieved explosive asset growth.
The Classic Case: The J-Com Incident In 2005, a Mizuho Securities trader made a monumental blunder—a "fat-finger error." Attempting to sell 1 share of J-Com stock at 610,000 yen, they accidentally entered "sell 610,000 shares at 1 yen each." B.N.F. spotted this rare opportunity within minutes. He judged that Japanese stock market rules wouldn't allow such an absurd erroneous trade to stand; it would inevitably be reversed or corrected. Acting swiftly, he deployed nearly all his liquid capital at the time, buying massive quantities of J-Com stock in minutes. He made over 2 billion yen in a single day.

In this case, he had zero time for calculation. His decision boiled down to: "This is a 100% certain money-making opportunity. All I need to do is buy as many shares as I can, as fast as I can."

A Reminder for Ordinary Investors

B.N.F.'s success was built upon extraordinary focus, ironclad discipline, a unique trading system, and the specific context of his era. His all-in "gambler" strategy was, for him, "calculated risk-taking." But for the vast majority of people, it's pure gambling.

His approach can be summarized as:

Calculation Method: A rapid qualitative assessment based on opportunity certainty, not complex quantitative models.
Capital Allocation: Tending to deploy all or the vast majority of available funds, concentrating investments on opportunities where confidence is extremely high.

Ordinary investors should NOT attempt to mimic this lightly! His story is inspirational, but his methodology, without his level of intuition and discipline, is an express train to bankruptcy. What we should learn from him is his intense dedication to market study and perseverance, not his high-risk capital management style.