What the Last 12 Months of Price Data Say About a Stock or Fund

What you need

The snapshot template on this page is optional, and this prompt does not use it: the summary concerns one holding's prices and leaves your balances aside. Fill in these lines in the prompt instead:

• Holding: [ticker or fund name]
• Current price and currency: [price and currency]
• Price 30 days ago: [price]
• Price 12 months ago: [price]
• 12-month high and low: [high] / [low]
• Base currency and exchange rates: [your currency, the rate 12 months ago and today, or "same"]

Your broker's app or any finance site with a one-year price chart shows all of these. Take every price from the same listing. A company traded in Amsterdam and New York has two prices in two currencies, and mixing them produces a return that never happened. Closing prices are the easiest to compare.

The last line matters when the holding is priced in one currency and you count your money in another. Note the exchange rate on both dates, from your bank or a central bank's published rates, and the model can show what the move was worth to you. If you leave out a figure, the prompt tells the model to ask for it instead of filling the gap with a guess.

Here is my financial snapshot. Use only these numbers.

Currency: [e.g. EUR]
Date: [today's date]
Age: [optional]

ASSETS
[name] — [category: cash / stocks / ETFs / crypto / property / metals / other] — [value]
[name] — [category] — [value]
...

LIABILITIES
[name] — [type: mortgage / car loan / credit card / student loan / other] — [outstanding balance] — [interest rate if known]
...

CONTEXT (optional but improves the answer)
Monthly income after tax: [amount]
Monthly spending: [amount]
Amount I add to savings or investments each month: [amount]
Value of the same assets 12 months ago: [amount]

The prompt

Copy this exact text and paste it into ChatGPT, Claude or Gemini directly beneath your snapshot block.

You are a market data analyst explaining one holding to a private investor.

Holding: [ticker or fund name]
Current price and currency: [price and currency]
Price 30 days ago: [price]
Price 12 months ago: [price]
12-month high and low: [high] / [low]
Base currency and exchange rates: [currency, rate then and now, or "same"]

1. Calculate the 30-day and 12-month price change in percent. Show the arithmetic.
2. Say where the current price sits between the 12-month low and high, and how
   far below the high it is.
3. If my base currency differs, show the 12-month change in my currency and
   explain how much the exchange rate added or took away.
4. Say what kind of holding this is (broad index fund, sector fund, large or
   small company) and what moves of this size are usual for that kind.
5. List what price data cannot show, such as dividends paid or why it moved.

Use only the figures above. If you cannot browse, say that you have no live
prices. If a figure is missing, ask me for it instead of estimating. No price
forecasts, no buy, sell or hold opinion and no other holdings to consider.

What good output looks like

A good answer opens with the two percentage changes and writes out each division so you can check it. Say you pasted these invented figures for a US-listed share: $56.00 today, $53.20 thirty days ago, $50.00 twelve months ago, a high of $60.00 and a low of $46.00. The model should report +5.3% over 30 days and +12.0% over 12 months.

The range step follows. The price sits 71% of the way from the low to the high ($10.00 of a $14.00 range) and 6.7% below the high. A careful answer adds that a price near the top of its range describes the past year and carries no signal about the next one.

The currency step often changes the picture. If you count in euros and the euro rose from 1.08 to 1.17 dollars, the share went from €46.30 to €47.86. The 12.0% gain in dollars became 3.4% in euros because the dollar weakened.

The comparison with similar holdings should be specific. A yearly range of about 30% of the low price is common for a single company and would be large for a broad index fund. The answer ends by naming what the prices leave out, starting with any dividends paid during the year.

What this can't tell you

Everything rests on the few prices you typed. A chat model that cannot browse has no live prices at all, and one that can may quote a different listing or an old figure, so check anything it adds against your broker. Five prices also hide the path between them, including how often and how sharply the price swung.

A price change leaves out dividends, fees and taxes, so it differs from the return you earned. How a gain is taxed depends on the rules in your country, which the model does not know. Recalculate the percentages yourself, since models slip on division and on which way to apply an exchange rate. Past moves say nothing reliable about the next twelve months.

Doing this without the retyping

On this page you look up five prices and two exchange rates before each run. In Sumio, "Market Data Summary" is one of the 62 prompts built into the AI assistant, a Premium feature. It runs on a stock or fund you already track, and the app adds the holding's 30-day and 12-month price history itself. Your records are stored on your device; running the analysis sends the figures it needs to an AI provider.