Finance & bookkeeping · Claude Code

Turn a trade log into an Excel portfolio tracker with live formulas

Idea + starter prompt, not run by us yet

For: Individual investors who keep trades in a spreadsheet and want a proper tracker

Claude Code gets three things: where the trade log lives, the starting cash and the start date, plus a rule to use real Excel formulas instead of typed numbers. It reads the log, fetches prices and company info with yfinance and builds the sheets. Then the user confirms the totals update when inputs change.

Steps

1. Make a copy of your trade log and point Claude Code at the copy.
2. Paste the starter prompt with your starting cash and start date.
3. Ask it to write to a new file, not the original.
4. Change one price by hand and check that the totals update. Tell it to fix any typed-in values.
5. Add broker downloads or a daily update script only after the basics work.

Starter prompt

Build a portfolio tracker in a new Excel file from my trade log at [path to copy of trade log]. Starting cash: [amount]. Start date: [date].

Use Excel formulas for every total. Do not type in fixed numbers. Pull current prices with a Python library and show me where each price came from.

First describe the sheets you plan to make. Write only to [new file name].xlsx and never edit my original log. When done, tell me which cell to change so I can test that the formulas update. This is for tracking only, not advice.

Original post: Substack · found via agentusecases.ai. Written up in our own words. We haven't run it, so test it on made-up data first.