A simple 'top 100' list on a trading app can move billions of dollars and permanently change a stock's price.
April 16, 2026
Original Paper
The List Effect: How App-Based Stock Rankings Drive Retail Trading and Market Prices
SSRN · 6582150
The Takeaway
We like to think stock prices move based on earnings and value, but this paper shows that Robinhood's '100 Most Popular' list acts as a massive coordination engine. When a stock enters that list, retail investors pile in simultaneously, driving the price up in a way that *doesn't* reverse. It’s not 'informed' trading; it’s just a UI design choice that forces thousands of people to look at the same thing at the same time. This means that a software designer has more power over market prices than many hedge fund managers. For you, it’s a reminder that what you think is 'doing your own research' is often just following a path laid out by an app's interface.
From the abstract
We show that Robinhood’s "100 Most Popular" list—a ranking of the 100 most widely held securities on the platform—acts as a salience mechanism that synchronizes the trading behavior of millions of retail investors. Stocks newly entering the list are up to 5.6 times more likely to be purchased in the days following the listing event, generating cumulative abnormal returns of approximately 26% by the listing date. Critically, these returns are not subsequently reversed: CARs remain elevated for up