I added my fourth contract at exactly the wrong time. Kelly said I had the edge. My equity curve said add size. The market said get bent — and I gave back three months of gains in two weeks. The maths was right. The execution destroyed me.
Here's what Kelly percentage and fixed fractional never tell you: they assume you can cut position size instantly when you lose. In futures, you can't. You trade whole contracts. One day you're trading two lots, next day the formula says 1.73 lots — good luck with that. So you round up, overtrade your account, and when the drawdown hits, it hits like a freight train. Ryan Jones saw this in the late 1990s and built fixed ratio position sizing to solve it. Instead of risking a percentage of equity, you add contracts based on a fixed dollar amount called the delta. Win $5,000? Add a contract. Lose back to your previous threshold? Drop a contract. It compounds slower than Kelly early on, but it doesn't blow you up when variance spikes.
The delta is your safety valve. Set it too low and you're Kelly all over again — aggressive compounding with brutal drawdowns. Set it too high and you barely scale at all. Jones recommended starting conservative: $5,000 delta for emini futures, $2,500 for forex mini lots. I tested $3,000 on the SPI. First six months felt glacial — I was still on two contracts while my Kelly-using mate was on five. Then his drawdown came. He dropped from five contracts to two in a week, watching his account whipsaw. My fixed ratio account just... didn't move. One contract down, equity stable, sleep undisturbed.
The real genius is in the threshold structure. To jump from one contract to two, you need delta dollars ($3,000). But to jump from two to three, you need $6,000 more — double the hurdle. Three to four? $9,000. The increments scale with your position size, which means your risk scales proportionally too. It's position sizing that respects the reality of whole contracts and the psychology of compounding. I stopped using Kelly eighteen months ago. Fixed ratio with a $3,000 delta, strict stop losses, and I track every threshold in a spreadsheet. When I hit $32,000 in profit on two contracts, I add the third. If I drop back below $26,000, I cut back to two. No emotions. No rounding errors. The method works because it acknowledges what Kelly criterion ignores: you can't trade 0.4 of a futures contract, and trying to force the maths into real execution will wreck you. Jones built a system for traders who use instruments with leverage and whole-unit sizing. It's slower, safer, and it actually survives contact with variance. The market rewards patience compounded correctly.
This content is educational only and does not constitute financial advice. Past performance is not indicative of future results. Always seek licensed financial advice before trading.