AMD Stock Pops on OpenAI Deal; AppLovin Plunges

A semiconductor stock logged the top performance in the benchmark index following the announcement of a collaboration with a major artificial intelligence player. Meanwhile, shares of an adtech darling plummeted following reports of a probe by federal regulators.

The S&P 500 rose 0.4% and the Nasdaq climbed 0.7% to set fresh closing record Monday, boosted by broader tech gains, while the Dow slipped 0.1%. See here for more reporting from Investopedia on the first day of the trading week.

Advanced Micro Devices (AMD) shares added nearly a quarter of their value in Monday’s session, outpacing every other stock in S&P 500, after the chipmaker announced a major artificial intelligence partnership with OpenAI. The ChatGPT owner, which recently surpassed SpaceX as the world’s most valuable startup, agreed to purchase several generations of AMD’s AI chips in a long-term deal that could also see OpenAI acquire a stake in the semiconductor firm.

Other stocks with exposure to AI infrastructure also moved higher following the announcement from AMD and OpenAI. Shares of Monolithic Power Systems (MPWR) and AI server maker Super Micro Computer (SMCI) added over 5%. DoorDash (DASH), and Uber (UBER), which got a shoutout from OpenAI during its DevDay developer conference, were also among the day’s top performers.

Tesla’s (TSLA) stock climbed 5.5% after the EV maker teased a Tuesday event that raised speculation the company could announce a lower-priced EV. During the company’s earnings call in July, executive had suggested Tesla would make “more affordable models” available in the fourth quarter of this year.

AppLovin (APP) shares tumbled 14%, suffering the heaviest losses in the S&P 500 following reports the Securities and Exchange Commission has been looking into its data collection practices. Despite Monday’s losses, the stock is up about 80% for 2025.

Verizon (VZ) shares sank 5.1% after the telecom giant named former PayPal (PYPL) chief Dan Schulman as its new CEO, effective immediately. Schulman, who has served on Verizon’s board since 2018, is replacing Hans Vestberg, who will remain on the board of directors and serve as a special advisor over the coming year as the telecom giant aims to close out its pending acquisition of fiber-optic internet provider Frontier Communications.