The Workshop · lesson 7
The same rules at half size and at double size are three different products.
These are the desk's own rules, replayed month by month since 2019 after costs, against the S&P 500 over the same months. The slider scales the book — half size, full size, double. Nothing else changes: same trades, same exits.
| book at 1.0× | S&P 500 |
|---|
At 1× the book returns less than the index with far less swing. Around 1.6× it matches the index's volatility and beats its return with a worst drawdown less than half the size. Push to 2.5× and the return keeps rising — and so does the drawdown, and so does the interest bill, and the summer of 2026 becomes a fall you would have felt in your sleep.
Fact. This is how professional desks pursue return: a proven ratio, scaled. A 1.0-Sharpe book at 12% volatility is an asset; a 0.5-Sharpe book at 20% is the index with extra steps. Leverage does not create edge, it multiplies whatever is there — including the bad months. Every number here is a replay; the live record on the engine page is the one that counts.
Three places. Borrow costs and margin calls are real above 1×. The replay assumes fills at the close; size adds slippage. And the worst drawdown in a replay is the worst so far, not the worst possible — every strategy's true worst drawdown is still ahead of it. Size to the drawdown you can hold, then halve it.
Your account size and per-position percentage in Account are this dial for your own book: a full line is account × percentage, so 5% is twenty slots, the same shape as the house. Raise the percentage and every line sizes up together; the closed view shows your worst drawdown beside your return so you can see what the dial cost.
Keep this: seek return by scaling a stable engine, never by loosening its rules — and size to the fall, not to the gain.
The Workshop is education, not advice. Replayed numbers are averages over many trades, after costs unless stated, and are not forecasts; the live record is on the engine page. Open the deskManualEngineChangelog