For writers, editors and curious people

Underfolio, at a glance.

The market has done this before. Underfolio lets you ask when, count what followed, and test your own read of the past.

A research tool and a blind trading game, built by Crystl Labs. The site is underfolio.com.

A short description

Underfolio is a market history research tool from Crystl Labs. Test a market question against past episodes, explore stocks that disappeared, and trade a stretch of history without knowing the year.

What people can do

• Ask what happened next. The Market Lab finds historical episodes matching a question and shows the outcomes alongside an ordinary-day comparison.
• Test a chart or a rule. Explore price history, indicators and patterns, including securities that stopped trading.
• Read the Graveyard. Follow a stock from its high to its last recorded trade, with the reason it left when the data provides one.
• Play the Daily Drop. Trade 20 weeks with $10,000 in simulated money, then guess the year. Everyone gets the same stretch; no account is needed.

The public history pages and guest Daily Drop are free. Research features have free account limits and a paid Pro option. Current prices and access.

What the numbers cover

Coverage varies by series and period. The US stock history uses CRSP from 1968 through 2024, with partial coverage back to 1962 and a separate source after 2024. Some index history extends to 1927. The pages show their coverage and last price date.

Delisting returns use a proxy; many older stocks have daily closes without full intraday candles. Shares and market values after 2024 are estimates. A historical result is not a forecast. Read the methods, sources and limits.

Screenshots

Captured October 1, 2026. Figures in these images are a snapshot; the site updates as new data arrives.

Logo

Underfolio — one word, capital U.

Download logo (PNG) · Download square icon (PNG)

These supplied screenshots and logo files may accompany coverage of Underfolio. Credit Underfolio / Crystl Labs and link to underfolio.com. Keep the images intact; this does not grant redistribution of the underlying market data.