Robinhood’s stock — which posted eye-popping gains earlier this week following last week’s lackluster IPO — fell 28 percent on Thursday after a group of investors filed to sell nearly 100 million shares in the company.

Early shareholders of the Silicon Valley-based free trading app — including venture firms like Andreessen Horowitz, as well as investors that bailed the company out of a liquidity crisis earlier this year — revealed in a Thursday filing with the SEC they have registered to sell a whopping 97.9 million shares

Robinhood shares ended the day at $50.97. A day earlier, the stock had surged 50 percent to $70.39 amid frenzied options trading, pushing it into the volatile “meme stock” category alongside names like GameStop and AMC.

Despite Thursday’s drop, Robinhood is still up almost 45 percent this week. Not only will the massive share dump likely to pressure the stock for several trading sessions, it is set to nearly triple the number of shares available for trading, which currently stands at just 55 million.

On the positive side, that could also take the edge off the stock’s volatility, according to some market participants.

“Today’s trading is just taking a bit of froth out of the stock,” Tim Anderson, managing director at TJM Investments told The Post. “They’re not going to look to destroy the price of the stock they’re just going to take advantage of the hyperbolic moves.”

Early investors of any company look to cash out on their bets, Anderson adds. In the case of Robinhood, some were firms that came to Robinhood’s rescue in January and February as the app was forced by regulators to pony up cash to hedge itself against wild market swings and make sure it had enough cash to clear trades.

In addition to Andreessen Horowitz, investors cashing out include New Enterprise Associates, which owns more than 10 percent of Robinhood. Others include Iconiq Capital, Institutional Venture Partners and Ribbit Capital, according to securities filings.

Apart from today, it’s been a bumper week for the popular retail trading app.

Moments after the opening bell on Wednesday, the stock climbed as high as $85 — up a staggering 81 percent from Tuesday’s closing price of $46.80 and briefly giving the company a market capitalization of more than $71 billion. That’s pricier than Intercontinental Exchange, which owns the New York Stock Exchange.

The rally marked a stunning turnaround for the stock, which last week had sunk more 10 percent in a disappointing IPO before finishing its first trading session below $35 a share.