Leverage amplifies everything — gains, losses, and the cost of getting your position size wrong. Position sizing is the risk management decision that matters most, and it's the one most traders spend the least time thinking about.
The Kelly criterion and why it's misapplied
The Kelly criterion is a formula for optimal bet sizing given known win rates and payoffs. In theory, it maximizes long-run wealth growth. In practice, it's almost always misapplied in trading contexts because the inputs — your actual win rate and average win/loss size — are almost never as stable as the formula assumes.
The more important insight from Kelly is the direction: overbetting destroys more value than underbetting. A half-Kelly position grows slower than a full-Kelly one but is dramatically more robust to variance. For levered positions where being right but sized wrong can wipe you out before you're vindicated, this asymmetry matters a lot.
Margin and leverage as position sizing levers
In a perpetual DEX, you have two inputs that jointly determine your position exposure: the notional size of the position and the leverage multiple. A $1,000 margin at 10x leverage gives you $10,000 in notional exposure. The same $1,000 at 5x gives you $5,000.
The common mistake is to think of leverage as the risk variable and margin as fixed. In practice, they're both free variables. If you want $10,000 notional exposure and are willing to risk $1,000, you can get there with $1,000 at 10x or $500 at 20x. The exposure is the same; what changes is how much buffer you have before liquidation.
The liquidation math
Your liquidation price depends on your entry price, your leverage, and the maintenance margin requirement. At 10x leverage with a 0.5% maintenance margin, a roughly 9.5% adverse move takes you to liquidation. At 25x, that's roughly 3.5%. These aren't abstract percentages in crypto markets — 3.5% intraday moves are routine.
The practical implication is that high-leverage positions require either very tight stop losses or a willingness to be liquidated occasionally as part of the strategy. Neither is inherently wrong, but knowing which one you're doing before you open the position is non-negotiable.
Sizing for the downside scenario
Position sizing should start from the answer to: "What's the most I can lose on this trade without materially affecting my ability to continue trading?" That's your risk budget. Work backward from there to the appropriate margin and leverage combination. Don't start from the leverage you want and work forward to the margin; that's how you end up with a liquidation threshold that gets touched during normal market volatility.
The 1% rule and why it's a starting point, not a rule
The conventional wisdom in professional trading is to risk no more than 1-2% of total capital on any single trade. At 10x leverage with 1% capital risk, your position notional is 10% of your total capital. A 10% adverse move against the position (roughly matching the notional) costs you 1% of capital. That's the math.
The 1% rule breaks down in crypto because of funding costs and the distribution of outcomes. In a market where 20% intraday moves are not unusual on smaller assets, a 1% stop loss placed at the maintenance margin boundary will trigger regularly on volatility that has nothing to do with your trade thesis. Proper position sizing in crypto requires understanding the asset's typical volatility, not just applying a fixed percentage rule from equity trading.
Volatility-adjusted sizing
A better approach is to size positions based on the asset's realized volatility. If BTC has a 30-day realized volatility of 55% annualized, that's roughly 3.5% daily. A position sized to risk 1% of capital on a 3.5% adverse daily move implies a notional exposure of about 28% of capital at 1x leverage (0.01/0.035). At 5x leverage, the same risk budget means 5.6% of capital in notional exposure.
Higher-volatility assets get smaller notional allocations for the same capital risk. This is how you avoid the situation where a 10x position on SOL wipes 5% of your account because the asset moved 3% in the wrong direction during a liquidity event.
Our data shows that the traders who survive their first 6 months on a leveraged platform share one characteristic: they size conservatively early on. Not because they're risk-averse by temperament, but because they understand that capital preservation is what keeps you in the game long enough to compound the wins.
Managing multiple positions simultaneously
Running multiple leveraged positions simultaneously multiplies both the opportunity and the risk management complexity. Correlation matters: two long positions on BTC and ETH aren't two independent bets. They're one highly correlated bet with twice the notional exposure. In portfolio terms, you should size correlated positions as if they're a single position with combined risk.
A simple rule: before opening a second position that's correlated with an existing one, ask whether you'd be comfortable with the combined notional if both positions moved against you simultaneously. If the answer is no, the second position is too large.
When to add to a position
Adding to a winning position (pyramiding) is a legitimate strategy, but it changes your position's average entry and liquidation dynamics. Adding to a losing position (averaging down) is almost always a mistake on leveraged instruments — it increases your notional exposure at exactly the moment the market is telling you your thesis is wrong. The asymmetry between the two is stark, and it's worth being explicit about the rule before you're in a live position and tempted to break it.
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