Nvidia (NVDA) shares are falling in premarket trading on "triple witching" day, when stock options, stock index futures, and stock index options contracts expire simultaneously; Gilead Sciences (GILD) is continuing to gain after the biotech firm's study found its lenacapavir drug effective in preventing HIV in women; shares of biotech Sarepta Therapeutics (SRPT) are soaring after U.S. regulators gave its gene therapy to treat a muscle-wasting disease broader approval; shares of fast-casual restaurant chain Chipotle Mexican Grill (CMG) are in focus ahead of its 50-for-1 stock split next Wednesday; and CarMax (KMX) shares are gaining even though the used-car retailer’s quarterly results lagged Wall Street forecasts. U.S. stock futures are falling after Nvidia's declines Thursday snapped a winning streak of record highs for the Nasdaq and S&P 500. Here's what investors need to know today.

Nvidia (NVDA) shares are falling 1.5% in premarket trading, extending Thursday declines that toppled the artificial intelligence (AI) chipmaker from its spot as the world’s most valuable company. Microsoft (MSFT) reclaimed that title on Thursday and its stock was little changed in premarket trading. Nvidia, whose shares are up more than 160% this year amid the frenzy for all-things AI, will especially be in focus as “triple witching” occurs Friday. That’s the quarterly event when stock options, stock index futures, and stock index options contracts expire simultaneously on the same trading day, and can lead to heightened market volatility. Triple witching happens on the third Friday of March, June, September, and December.

Gilead Sciences (GILD) is extending gains from Thursday, rising 3% in premarket trading after the biotech firm announced a Phase 3 trial found its injectable lenacapavir was 100% effective in preventing HIV infection in women. Gilead said that the results were so successful that an independent data monitoring committee recommended that the company end the blind phase of the study and offer lenacapavir to all of the participants.

Shares of biotech Sarepta Therapeutics (SRPT) are soaring 37% in premarket trading, extending gains from Thursday, after U.S. regulators gave its Duchenne muscular dystrophy treatment approval to be rolled out for broader access. The Food and Drug Administration (FDA) gave Elevidys approval to be offered to all patients 4 and older after previously just allowing it for 4- and 5-year-olds. The disease is “a rare and serious genetic condition which worsens over time, leading to weakness and wasting away of the body’s muscles,” the FDA said.

Shares of fast-casual restaurant chain Chipotle Mexican Grill (CMG) are up less than 1% following a 6.2% decline on Thursday, their largest daily percentage loss since last July. The slump comes ahead of a 50-for-1 stock split that takes effect next Wednesday, an event that will make the company's shares more accessible to more investors. The stock has gained more than 40% since the start of the year and has more than doubled since the start of 2023.

CarMax (KMX) shares are gaining 1.2% in premarket trading even though the used-car retailer’s quarterly results lagged Wall Street forecasts. The company announced, however, that it was expanding its asset-backed securitization program so it could boost its finance income. The company reported first-quarter fiscal 2025 net sales of $7.11 billion, down 7.5% from $7.69 billion the same period last year and below the $7.23 billion expected by analysts polled by Visible Alpha. Earnings per share (EPS) of $0.97 also came below the $0.98 forecast. Retail used unit sales decreased 3.1% and wholesale units declined 8.3% from last year, "impacted by lower year-over-year seasonal appreciation," CarMax said.

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Regulators in the U.K. are investigating Live Nation Entertainment's (LYV) Ticketmaster unit over reported customer issues with tickets purchased for the recently announced reunion tour of the 90s band, Oasis, specifically whether the company's "dynamic pricing" feature may have violated consumer protection laws.

The Competition and Markets Authority (CMA) said that it wants to hear from fans who feel they may have been misled during the purchasing process about what price they would end up paying or pressured to buy tickets out of fear that the price could go up soon after, both of which could be deemed violations of consumer protection laws.

The agency said the opening of its investigation doesn't necessarily mean Ticketmaster broke any laws, and said it wants to hear from those affected over the next two weeks as it also gathers information from Ticketmaster and other parties.

"It’s important that fans are treated fairly when they buy tickets, which is why we’ve launched this investigation. It’s clear that many people felt they had a bad experience and were surprised by the price of their tickets at check-out," said CMA Chief Executive Sarah Cardell. "We want to hear from fans who went through the process and may have encountered issues so that we can investigate whether existing consumer protection law has been breached."

The UK regulator also said it has previously called for more extensive protections for ticket buyers, and that it is considering broader action against the practice of dynamic pricing—in which prices can change rapidly based on demand—in industries aside from ticketing.

Live Nation and Ticketmaster are already facing legal action in the U.S., as the Department of Justice filed a lawsuit in May accusing the company of monopolistic behavior and violating antitrust laws. The suit claimed Live Nation often threatens or retaliates against venues that choose a ticket seller other than Ticketmaster, and said its fees are excessive for consumers.

Live Nation shares were nearly 1.2% lower at $93.10 Friday afternoon.

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