The Scenario
You inherited the portfolio tracking sheet from someone who left three months ago. Column A has 10 tickers. There are empty columns B through H with headers that say things like Open, High, Low, Close, Volume — all blank. Somewhere in the handoff notes it says "update this weekly from Marketstack," but there are no instructions for how.
You have a Marketstack API key. You have the sheet. The gap between those two things is the problem.
The bad version:
- Open the Marketstack docs, find the end-of-day endpoint, construct a URL with your ticker, date range, and API key, and run it in a browser
- Parse the JSON manually, figure out which array index is "open" versus "high," copy the values into your sheet row by row for 252 rows — then repeat for all nine remaining tickers
- Realize on ticker 6 that the date sort is descending, not ascending, go back and flip the first five sheets, and add another 40 minutes to the project
This is not the kind of work that fits inside a lunch break. You are supposed to be doing performance analysis, not writing data transport scripts.
The Easy Way: One Prompt in SheetXAI
SheetXAI is an AI agent that lives inside your Google Sheet. It reads the sheet, sees the ticker list in column A, and through its built-in Marketstack integration it can pull full OHLCV histories for every ticker and write them into the sheet — without you touching the API.
For each ticker in column A, fetch the last 252 trading days of end-of-day OHLCV data from Marketstack and write date, open, high, low, close, and volume into a new tab per ticker, sorted by date ascending
What You Get
- A new tab for each ticker in column A — named after the ticker symbol
- Columns in order: Date, Open, High, Low, Close, Volume — 252 rows each
- Dates sorted ascending so the most recent row is at the bottom
- Any ticker that returns no data gets a tab with a note explaining why (invalid symbol, exchange not supported, etc.)
What If the Data Is Not Quite Ready
The ticker list has both symbols and company names mixed together
Column A has a mix of ticker symbols (like AAPL) and company names (like Apple Inc) — for each row, figure out the correct Marketstack ticker symbol first, then fetch the last 252 trading days of OHLCV and write them into a new tab named after the resolved ticker
You only want tickers from US exchanges
For each ticker in column A, fetch the last 252 days of OHLCV data from Marketstack — but only write the tab if the ticker's primary exchange is a US exchange; add a note in the Summary tab for any ticker that is listed on a non-US exchange
The date range needs to match a specific lookback window in another column
Column A has tickers, column B has a start date for each — for each ticker, fetch OHLCV data from Marketstack starting at the date in column B through today, and write the results into a new tab per ticker
Full pipeline: resolve symbols, pull history, calculate annualized volatility
For each ticker in column A, confirm the symbol is valid in Marketstack, then fetch the last 252 trading days of close prices, write them into a tab per ticker, and add a Summary tab showing each ticker's annualized volatility calculated from the daily log returns
Combining the validation, the data pull, and the calculation in a single prompt is how you avoid the back-and-forth of doing each step separately and finding problems only at the end.
Try It
Get the 7-day free trial of SheetXAI and open the sheet with your ticker list in column A, then ask it to pull a full year of OHLCV history from Marketstack for every row. The Marketstack integration is included in every SheetXAI plan.
See also: refreshing a watchlist with latest prices and building dividend history tables.