Position Sizer
Risk-based position sizing for long stock trades: fixed-fractional, ATR-based, and Kelly criterion methods, with portfolio and sector concentration limits.
- What
- Risk-based position sizing for long stock trades: fixed-fractional, ATR-based, and Kelly criterion methods, with portfolio and sector concentration limits.
- Cost
- Free
- Needs
- Use "Position Sizer" with your Muse.
- Install
- Copy the installer prompt below into your Muse — your agent does the rest.
⚠️ **Trading warning / Avertissement trading** : informational only, not investment advice. Correct position sizing limits how much a losing trade hurts; it does not make a trade profitable, and trading still involves real risk of loss. Curated by Skill Harbor: a focused calculator that answers "how many shares?" from a risk budget instead of a hunch. It supports three methods: fixed fractional (risk a set percentage of account equity per trade, 1% by default, using the distance from entry to stop), ATR-based sizing (the stop distance comes from the stock's Average True Range times a multiplier, so volatile names automatically get smaller positions), and the Kelly criterion (size from your historical win rate and average win/loss). Portfolio guardrails apply on top of every method: a maximum position size as a percentage of the account and a maximum sector exposure, with the final recommendation given as a full risk breakdown. Output defaults to whole shares; an optional fractional mode with configurable precision serves small accounts or high-priced stocks when the broker supports fractional shares. It runs on Python 3.9+ with the standard library only, and needs no API keys: you supply account size, entry, and stop (or ATR, or your win/loss statistics). From the tradermonty/claude-trading-skills repository (MIT). Honest caveats: long stock trades only, no shorting, options, or futures sizing. The math assumes your stop actually executes near its price; gaps and slippage can make a real loss larger than the planned risk, and full Kelly output is famously aggressive, which is why the portfolio caps matter. Skill Harbor never reviews the code, review it yourself before use.
Version:
Install
Copy the install package below, then paste it into MuseThe install prompt below already includes the vetting steps: your agent follows the community checklist before installing anything with executable code. Want more?
Use "Position Sizer" with your Muse. 1. Open the skill: https://github.com/tradermonty/claude-trading-skills/blob/main/skills/position-sizer/SKILL.md and copy the full SKILL.md text. 2. Paste it into a chat with Muse and add: "Size this trade: account $[amount], entry $[price], stop $[price], risk 1%" or "Use ATR sizing: ATR is [value], multiplier 2." 3. Check the breakdown before trading: shares, dollars at risk, position size as a percentage of your account, and sector exposure after the trade. Tip: if whole-share rounding under-deploys your risk budget on a high-priced stock, ask about the fractional mode, only if your broker supports fractional shares for that order type. Safety: a skill is plain-text instructions; it runs nothing by itself. Trading involves real risk of loss; this is informational only, not investment advice.
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Questions
How do I install a build?
Every product page includes a copy-paste install prompt. Paste it into your Muse and it sets the build up for you — no manual configuration.
Where does my money go?
Straight to the seller. Skill Harbor never processes payments: checkout happens on the seller’s own page, usually Stripe.
What does the ✓ next to a creator’s name mean?
It means we confirmed the identity of the person behind the listing. It says nothing about the code itself — always check a build before installing it.