position-sizer

SKILL.md

Position Sizer

Overview

Calculate the optimal number of shares to buy for a long stock trade based on risk management principles. Supports three sizing methods:

Fixed Fractional: Risk a fixed percentage of account equity per trade (default: 1%)

ATR-Based: Use Average True Range to set volatility-adjusted stop distances

Kelly Criterion: Calculate mathematically optimal risk allocation from historical win/loss statistics

All methods apply portfolio constraints (max position %, max sector %) and output a final recommended share count with full risk breakdown.

When to Use

User asks "how many shares should I buy?"

User wants to calculate position size for a specific trade setup

User mentions risk per trade, stop-loss sizing, or portfolio allocation

User asks about Kelly Criterion or ATR-based position sizing

User wants to check if a position fits within portfolio concentration limits