On September 15 local time, the three major U.S. stock indices collectively closed higher. As of the close, the Dow Jones rose by 49.23 points, or 0.11%, to 45,883.45 points; the Nasdaq rose by 207.65 points, or 0.94%, to 22,348.75 points; and the S&P 500 rose by 30.99 points, or 0.47%, to 6,615.28 points.

By sector, six of the eleven major sectors of the S&P 500 fell, while five rose. The consumer staples and healthcare sectors led the declines with drops of 1.15% and 1.01%, respectively, while the communication services and consumer discretionary sectors led the gains with increases of 2.33% and 1.10%, respectively.

Most major tech stocks advanced. Alphabet, the parent company of Google, rose 4.5%, with a closing market capitalization of $3.04 trillion, becoming the fourth U.S. listed company to surpass a $3 trillion market cap, after Apple, Microsoft, and Nvidia. ASML rose over 6%, Tesla rose over 3%, Amazon, Meta, Apple, and Microsoft rose over 1%, while Nvidia closed down 0.04%.

Alphabet, the parent company of Google, rose 4.5%. The news is that due to the viral popularity of Gemini 2.5 Flash Image, nicknamed "Nano Banana," since its launch in late August, Google's Gemini app surpassed ChatGPT over the past weekend to become the most downloaded free app on the App Store and Google Play Store in multiple countries.

The Nano Banana trend involves transforming user-uploaded images into ultra-detailed 3D-style figurine images. Earlier on Monday, Citigroup's internet industry analyst Ron Josey raised Alphabet's target price from $225 to $280.

Tesla closed up 3.56%. According to a FORM 4 filing released on Tesla's website on Monday, the company's CEO Elon Musk spent approximately $1 billion to purchase 2.57 million Tesla shares last Friday (September 12). The filing showed that Musk's purchase price ranged from $371.9 to $396.359 per share.

According to Verity, such purchases are rare for Musk. His last purchase of about 200,000 Tesla shares was on February 14, 2020, worth approximately $10 million. According to Verity, this is his largest purchase ever.

Most popular Chinese concept stocks rose, with the Nasdaq Golden Dragon China Index closing up 0.87%. Li Auto rose nearly 7%, Bilibili rose over 6%, NIO, Hesai, and So-Young rose over 4%, Xiaomi Group (ADR) and XPeng Motors rose over 2%, while Alibaba, Pinduoduo, and NetEase rose over 1%.