Check out the companies making the biggest moves midday: Lyft — The ride-share stock surged 13%. Riders will be able to use the Lyft app to hail robotaxis from Alphabet's Waymo when service begins next year . Walmart — The retail giant added 2% following a price target lift from Bank of America . Analyst Robert Ohmes cited Walmart's status as an emerging leader in artificial intelligence within the retail sector as a catalyst. American Express — The credit card giant gained 2.7% and was the best-performing stock in the Dow Jones Industrial Average. The move comes ahead of an expected Federal Reserve rate cut later in the day. Visa and Mastercard also traded higher. Roivant Sciences — The drugmaker popped 11% after the release of positive Phase 3 trial results for its brepocitinibm drug, which aims to treat certain immune and inflammatory diseases. Nvidia — The artificial intelligence chip darling dropped 3% after a report by the Financial Times , which cited three people with knowledge of the matter, said China's internet regulator has banned the biggest tech companies in the country from buying Nvidia's AI chips. Shares of chipmaker Advanced Micro Devices also fell more than 1% in sympathy following the report. Alibaba — U.S.-listed shares of the Chinese e-commerce giant gained 2.6% after Chinese state media reported that the company won a major customer, China Unicom, for its artificial intelligence chips. Baidu — The Chinese tech company surged 7.7%. The move comes on the heels of Arete Research Services upgrading Baidu's American depositary receipts to buy from sell , citing a positive outlook for its AI chip and cloud-computing revenue. Cytokinetics — The stock fell more than 1%. On Tuesday, the biopharmaceutical company announced plans to offer $650 million in convertible senior notes due in 2031. Workday — Shares of the human resources software provider advanced 8% after activist investor Elliott Management disclosed a $2 billion stake in the company. Netflix — The streaming giant moved 1% higher on the back of an upgrade to buy from hold at Loop Capital. The firm said Netflix has won the streaming wars with its strong content and has higher longer-term margin assumptions as its content generates more revenue. Zillow Group — The stock climbed 4% after Bernstein upgraded it to outperform from market perform. The firm said it has been "warming up" to its fundamental story and cited the company's recent execution on revenue growth as a factor. — CNBC's Sarah Min, Sean Conlon, Lisa Han, Alex Harring and Michelle Fox Theobald contributed reporting.
