position-sizer

position-sizer is a skill for Claude Code, Codex from tradermonty/claude-trading-skills. It costs 62 tokens per session (1,844 once invoked), scanned A, original, MIT.

A calculator for deciding how many shares to buy in a long stock trade based on account risk, stop-loss distance, volatility, and portfolio limits. It supports fixed-percentage risk, ATR-based sizing, and the Kelly criterion, which estimates allocation from historical wins and losses.

In plain words
What is it for?
Use it for share-count calculations, stop-loss planning, volatility-adjusted sizing, fractional-share sizing, and checks on position or sector concentration.
Why use it?
It converts a chosen risk limit into a share count and checks whether the position is too large for the account or sector. This reduces guesswork when setting trade size.

Skill for Claude CodeCodex

Written for no agent in particular: nothing here depends on one.

not rated 2.8krepo +32 today A scan Socket: passSnyk: passSkillSpector: pass 62 tokens original MIT

Good fit Use it for share-count calculations, stop-loss planning, volatility-adjusted sizing, fractional-share sizing, and checks on position or sector concentration.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/tradermonty/claude-trading-skills/position-sizer
About the project

Claude Trading Skills is a collection of Claude Code workflows for individual investors who want structured market analysis, charting, economic-calendar review, screening, trade planning, journaling, and risk management. It is designed for people using long-term investing, ETFs, dividend stocks, and disciplined swing trading, and the catalogue entries package these workflows as skills, agents, commands, settings, and instructions.

tradermonty/claude-trading-skills · 2,813 stars · on GitHub · tradermonty.github.io

Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

Any agent
npx skills add tradermonty/claude-trading-skills --skill position-sizer
Clone the repo
git clone --depth 1 https://github.com/tradermonty/claude-trading-skills

Made for: Claude Code, Codex.

Wrote this? Show the measurements

A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.

agentmods badge for position-sizer

README.md
[![agentmods](https://agentmods.dev/badge/skills/tradermonty/claude-trading-skills/position-sizer/github.svg)](https://agentmods.dev/skills/tradermonty/claude-trading-skills/position-sizer)
Your own site
<a href="https://agentmods.dev/skills/tradermonty/claude-trading-skills/position-sizer"><img src="https://agentmods.dev/badge/skills/tradermonty/claude-trading-skills/position-sizer/github.svg" alt="Measured on agentmods" height="20"></a>

Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.

agentmods 80×15 button for position-sizer

Your own site · 80×15
<a href="https://agentmods.dev/skills/tradermonty/claude-trading-skills/position-sizer"><img src="https://agentmods.dev/badge/skills/tradermonty/claude-trading-skills/position-sizer.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 62 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 1,844 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe. Third-party audits
  • Socket pass 24 Mar 2026
  • Snyk pass 24 Mar 2026
  • NVIDIA SkillSpector pass 7 Sept 2026
How audits are shown
Origin original No closer match found in the catalogue.
Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

ModelPer sessionOnce invoked
Fable 5.1 $0.00062 $0.01844
Opus 5 $0.00031 $0.00922
Sonnet 5 $0.00012 $0.00369
Haiku 4.5 $0.00006 $0.00184

Measured 9d ago against content hash 0fca15a0976e, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-12, from the pricing page.

Security

Grade A, and why

position-sizer scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 9d ago.

The scan reads SKILL.md. This mod also ships 3 executable files (scripts/position_sizer.py, scripts/tests/conftest.py, scripts/tests/test_position_sizer.py), listed below but not scanned — reading those needs a real analyzer, not pattern matching.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Nothing flagged

None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.

skills/position-sizer/SKILL.md · 197 lines

How it starts

The opening of the file, as written. The whole thing — 197 lines — stays where its author put it; the contents beside it link to each section on GitHub.

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. The default output is whole shares. Use --fractional only when the user's broker supports fractional shares for the security and order type.

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 has a small account where whole-share rounding would under-deploy a defined risk budget
  • User wants to check if a position fits within portfolio concentration limits

Prerequisites

  • No API keys required
  • Python 3.9+ with standard library only

Workflow

Step 1: Gather Trade Parameters

Collect from the user:

  • Required: Account size (total equity)
  • Mode A (Fixed Fractional): Entry price, stop price, risk percentage (default 1%)
  • Mode B (ATR-Based): Entry price, ATR value, ATR multiplier (default 2.0x), risk percentage
  • Mode C (Kelly Criterion): Win rate, average win, average loss; optionally entry and stop for share calculation
  • Optional constraints: Max position % of account, max sector %, current sector exposure
  • Optional share mode: Whole shares by default, or fractional shares with --fractional --share-precision N when supported by the broker

If the user provides a stock ticker but not specific prices, use available tools to look up the current price and suggest entry/stop levels based on technical analysis.

Read the full file on GitHub · 197 lines

Files

What ships with it

5 files beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.

Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

  1. 9d ago First seen · 197 lines · 62 tokens per session scan A 0fca15a0976e

Subscribe to this mod's changes

position-sizer is a skill published in the GitHub repository tradermonty/claude-trading-skills (2,813 stars, last pushed today), licensed MIT. It adds 62 tokens to every session and 1,844 once invoked, about $0.0003 per session on Opus 5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-09-03.

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