Why size the whole book, not the trade
Short · Risk & sizing · October 7, 2026
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Any idea can miss. RAIL never traded above its entry — its second morning it opened 19% lower, right through a 14% stop, and never came back. All in, that gap alone is about a fifth of the account; at 8% of the book it's about one and a half percent.
Part of the full lesson: How much should I risk across all my trades? Portfolio heat
The lesson in writing
So you think, why not just go all in on your absolute best idea? Well, the because is right here: because any idea can miss.
How it's worked out
RAIL, a weekly signal from Olympia, never traded above its entry. Its second morning it opened 19% lower than it opened, right through a 14% stop, and it never came back to pay out.
All in, that gap alone is about one fifth of your account. At eight percent of the book, it's about one and a half percent.
You want to dig a deep hole, you're going to have a hell of a time climbing out: down 50%, you're going to need 100% just to get back to even.
Why it's worth doing
Now you spread your loss out, you cap it, you add up the risk — it's all one job.
No single punch can end a fight. No single loss can take you out. And this way even your best idea gets a seat at the table; it's never ever going to get the whole account.
The heat, the correlation and the caps that do the spreading are in How much should I risk across all my trades? Portfolio heat.
RAIL is a weekly signal from Olympia's own record: it never traded above its entry and opened −19.3% on the morning of Tuesday 3/10, read from the daily cache; the −14% stop is the stop menu's tight weekly rung. The account arithmetic is on the example $25,000 book. Measured and backward-looking, not a forecast.
