Investing.com -- Stock futures traded lower early Tuesday following a losing session a day earlier, though major U.S. benchmarks still managed to post monthly gains.

Dow Jones Industrial Average futures were down 0.65% at 05:51 ET (09:51 GMT), S&P 500 futures fell 0.62%, and Nasdaq-100 futures dropped 1.06%.

GoPro shares surged over 82% premarket after Bloomberg reported that YouTube creator Mark Fischbach, known as Markiplier, disclosed an 8.5% stake in the action-camera maker through a Schedule 13G filing, making him the company’s largest individual shareholder. Fischbach, who has nearly 40 million YouTube subscribers and has recently moved into Hollywood filmmaking, called the stock undervalued and said he wants to see the company turn around, comments that fueled a wave of retail buying.

Robinhood shares rose 2.6% after Morgan Stanley upgraded the stock to "Overweight" from "Equal-weight" and raised its price target to $150 from $124, implying 43% upside from the last close. The bank pointed to organic asset growth, active trader share gains, and newer products as catalysts supporting a longer growth runway than previously modeled. Morgan Stanley said Robinhood’s "expanding product set gives customers more reasons to consolidate assets on the platform and reduces graduation risk" as its largely Gen Y/Z customer base builds wealth and financial complexity.

Novartis shares climbed nearly 4% after the drugmaker reported a positive late-stage trial readout for its multiple sclerosis candidate remibrutinib, which significantly reduced relapse rates compared with an established treatment. The gains came despite reports that Novartis has paused a separate experimental treatment after three patient deaths; analysts said more details on the MS data were still needed.

Sono Group shares jumped about 55% after the company and privately held Sports One announced a non-binding letter of intent to combine. The deal would create a publicly traded, permanent-capital company acquiring minority stakes in NFL, NBA, MLB and NHL franchises, alongside a sports intelligence business serving athletes, teams, universities, brands and sponsors. The combined entity would be renamed Sports One and led by its management team, marking a full pivot away from Sono’s former identity as a digital asset treasury company.

Duolingo shares rose 3.8% after Evercore ISI analyst Mark Mahaney upgraded the stock to "Outperform" from "In Line" and doubled his price target to $210, implying more than 40% upside. The call was based on a valuation of 20 times 2028 EBITDA, with Mahaney raising his 2027 and 2028 EPS estimates to 10% and 25% above Wall Street consensus, respectively.