$npx -y skills add agiprolabs/claude-trading-skills --skill position-sizingTrade sizing methods including fixed fractional, volatility-adjusted, Kelly criterion, and liquidity-constrained sizing
| 1 | # Position Sizing |
| 2 | |
| 3 | Position sizing is the single most important risk management decision in trading. Your entry signal determines direction; your position size determines survival. A mediocre strategy with proper sizing will outperform a great strategy with reckless sizing over any meaningful time horizon. |
| 4 | |
| 5 | **Core principle**: Size determines survival, not entries. Two traders with the same signals but different sizing will have wildly different outcomes. The one who sizes conservatively survives drawdowns and compounds capital; the one who oversizes blows up. |
| 6 | |
| 7 | ## Methods Covered |
| 8 | |
| 9 | | Method | Best For | Key Input | |
| 10 | |--------|----------|-----------| |
| 11 | | Fixed Fractional | General trading, most recommended | Account risk % | |
| 12 | | Volatility-Adjusted | Volatile markets, multi-asset | ATR or realized vol | |
| 13 | | Kelly Criterion | Quantified edge with track record | Win rate + payoff ratio | |
| 14 | | Liquidity-Constrained | Low-liquidity Solana tokens | Pool depth | |
| 15 | | Anti-Martingale | Trend-following strategies | Recent P&L streak | |
| 16 | |
| 17 | --- |
| 18 | |
| 19 | ## 1. Fixed Fractional Sizing |
| 20 | |
| 21 | The most recommended method for most traders. Risk a fixed percentage of your account on each trade. |
| 22 | |
| 23 | ### Formula |
| 24 | |
| 25 | ``` |
| 26 | risk_amount = account_value * risk_percentage |
| 27 | price_risk_per_unit = entry_price - stop_loss_price |
| 28 | position_size_units = risk_amount / price_risk_per_unit |
| 29 | position_value = position_size_units * entry_price |
| 30 | ``` |
| 31 | |
| 32 | ### Risk Tiers |
| 33 | |
| 34 | | Tier | Risk Per Trade | Use Case | |
| 35 | |------|---------------|----------| |
| 36 | | Conservative | 0.5–1% | New strategies, drawdown recovery | |
| 37 | | Standard | 1–2% | Most traders, proven strategies | |
| 38 | | Aggressive | 3–5% | High-conviction setups with strong, measured edge | |
| 39 | |
| 40 | ### Example |
| 41 | |
| 42 | ```python |
| 43 | account = 10_000 # $10,000 or 100 SOL |
| 44 | risk_pct = 0.02 # 2% |
| 45 | entry = 1.50 |
| 46 | stop_loss = 1.30 |
| 47 | |
| 48 | risk_amount = account * risk_pct # $200 |
| 49 | price_risk = entry - stop_loss # $0.20 |
| 50 | position_units = risk_amount / price_risk # 1,000 tokens |
| 51 | position_value = position_units * entry # $1,500 |
| 52 | ``` |
| 53 | |
| 54 | With this sizing, if the stop loss is hit, you lose exactly 2% of your account regardless of the token's price or volatility. |
| 55 | |
| 56 | --- |
| 57 | |
| 58 | ## 2. Volatility-Adjusted Sizing |
| 59 | |
| 60 | Scale position size inversely with volatility. When volatility is high, take smaller positions; when low, take larger positions. This normalizes the dollar risk across different market conditions. |
| 61 | |
| 62 | ### Formula |
| 63 | |
| 64 | ``` |
| 65 | adjusted_size = base_size * (target_vol / current_vol) |
| 66 | ``` |
| 67 | |
| 68 | Where: |
| 69 | - `target_vol`: your desired daily portfolio volatility (e.g., 2%) |
| 70 | - `current_vol`: the token's current daily volatility (from ATR or realized vol) |
| 71 | |
| 72 | ### Using ATR |
| 73 | |
| 74 | ```python |
| 75 | atr_14 = 0.12 # 14-period ATR |
| 76 | close_price = 1.50 |
| 77 | daily_vol_pct = atr_14 / close_price # 8% |
| 78 | |
| 79 | target_daily_vol = account * 0.02 # $200 target daily move |
| 80 | position_size = target_daily_vol / atr_14 # 1,667 units |
| 81 | ``` |
| 82 | |
| 83 | This automatically reduces exposure in volatile markets and increases it in calm ones. |
| 84 | |
| 85 | --- |
| 86 | |
| 87 | ## 3. Kelly Criterion |
| 88 | |
| 89 | The mathematically optimal fraction of capital to risk, maximizing long-term growth rate. Derived from maximizing expected logarithmic utility. |
| 90 | |
| 91 | ### Formula |
| 92 | |
| 93 | ``` |
| 94 | f* = (p * b - q) / b |
| 95 | ``` |
| 96 | |
| 97 | Where: |
| 98 | - `p` = win rate (probability of winning trade) |
| 99 | - `q` = 1 - p (probability of losing trade) |
| 100 | - `b` = average win / average loss (payoff ratio) |
| 101 | - `f*` = optimal fraction of capital to risk |
| 102 | |
| 103 | Equivalent form: `f* = (p * (b + 1) - 1) / b` |
| 104 | |
| 105 | ### Critical Rule: NEVER Use Full Kelly |
| 106 | |
| 107 | Full Kelly assumes perfect knowledge of your edge. In practice, edge estimates are noisy. Always use fractional Kelly: |
| 108 | |
| 109 | | Fraction | Use Case | Notes | |
| 110 | |----------|----------|-------| |
| 111 | | 0.25x Kelly | Conservative, recommended default | Robust to edge estimation error | |
| 112 | | 0.50x Kelly | Moderate, for well-measured edges | Still significant drawdown risk | |
| 113 | | 1.0x Kelly | Never in practice | Theoretical maximum, catastrophic if edge is overestimated | |
| 114 | |
| 115 | ### Example |
| 116 | |
| 117 | ```python |
| 118 | win_rate = 0.55 # 55% win rate |
| 119 | avg_win = 2.0 # Average win is 2x the average loss |
| 120 | avg_loss = 1.0 |
| 121 | payoff_ratio = avg_win / avg_loss # b = 2.0 |
| 122 | |
| 123 | kelly = (win_rate * payoff_ratio - (1 - win_rate)) / payoff_ratio |
| 124 | # kelly = (0.55 * 2.0 - 0.45) / 2.0 = 0.325 = 32.5% |
| 125 | |
| 126 | quarter_kelly = kelly * 0.25 # 8.1% — use this |
| 127 | half_kelly = kelly * 0.50 # 16.25% |
| 128 | ``` |
| 129 | |
| 130 | **If Kelly is negative, you have no edge. Do not trade.** |
| 131 | |
| 132 | See `references/sizing_formulas.md` for the full mathematical derivation. |
| 133 | |
| 134 | --- |
| 135 | |
| 136 | ## 4. Liquidity-Constrained Sizing |
| 137 | |
| 138 | Critical for Solana tokens. Even if your risk model says you can take a large position, the pool may not support it without unacceptable slippage. |
| 139 | |
| 140 | ### Formula (Constant-Product AMM) |
| 141 | |
| 142 | ``` |
| 143 | slippage ≈ trade_size / pool_liquidity |
| 144 | max_trade = pool_liquidity * max_slippage_pct |
| 145 | ``` |
| 146 | |
| 147 | ### Rules of Thumb |
| 148 | |
| 149 | | Constraint | Guideline | |
| 150 | |-----------|-----------| |
| 151 | | Max single trade | 2% of |