Billionaires keep blaming Robinhood traders for skewing stock prices. But a new study says the upstarts have minimal impact on the overall market.

• The stock market has attracted a lot of new participants during the COVID-19 pandemic, including retail traders who flocked to zero-commission trading apps like Robinhood.
• As Robinhood surged in popularity, so did Robintrack, a third-party website publishing data on the number of Robinhood accounts that own a particular stock.
• The publicity about what Robinhood traders were buying and selling led some well-known investors to bemoan their rise and their effect on the stock market.
• But a study from Nick Maggiulli of Ritholtz Wealth Management found that Robinhood traders didn't have as big of an impact on the stock market as some might think.
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During the COVID-19 pandemic, the stock market saw a surge of new participants, as many people stuck at home with no sports to watch diverted their attention to the market.

One beneficiary of this new trend was the zero-commission brokerage app Robinhood, which has seen millions of new accounts open.

On top of that, Robintrack, a third-party website publishing daily updates on the number of Robinhood accounts that own a particular stock, has surged in popularity.

This put a target on the back of retail traders as a whole, and seasoned investors often blamed them for driving the stock market higher amid the sharpest economic decline since the Great Depression.

The billionaire investor Leon Cooperman said of the traders in July, "They are just doing stupid things, and in my opinion, this will end in tears."

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But a study published on Tuesday by Nick Maggiulli, the chief operating officer at Ritholtz Wealth Management, found that Robinhood traders have had little to no impact on the stock market overall.

Maggiulli scraped Robintrack for data on the 200 most popular stocks on the platform and compared that with their daily price moves. Maggiulli said he "wanted to test whether an increase (or decrease) in Robinhood users holding a stock was met with a similar increase (or decrease) in that stock's price."

The results? For most of the stocks studied, "there was little to no correlation between the one-day change in stock price and the one-day change in the number of Robinhood users holding them," Maggiulli said.

For example, Ford, the most popular stock on the Robinhood platform, had a correlation near zero, meaning the daily change in Robinhood account ownership had no effect on the daily change in Ford's stock price.

But Maggiulli found that smaller, speculative names like Kodak, Nikola, and Hertz had a higher correlation than bigger companies like Amazon, Google, and Tesla.

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"Since these are higher market cap stocks, it's possible that even lots of volume from Robinhood traders can't move the market, compared to, say, a stock like Hertz, which is trending toward being worth $0," Maggiulli explained.

While Robinhood traders may not affect the overall stock market, they have had a sizable effect in the financial-media space.

"Popularity on Robinhood is not predictive of price changes, but it is predictive of what will make the headlines," Maggiulli concluded.

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