Jensen Huang, CEO and founder of Nvidia, which makes chips used to train artificial intelligence ... [+] technology, takes part in a press conference at the Government Office in H

Nvidia ( NVDA -2.55%) has been a big beneficiary of the AI boom. Amazing sales growth propelled it to the world's leading semiconductor company by market cap, and the company's success makes it among the top AI stocks to buy.

Nvidia is the only stock in the Dow Jones Industrial Average this year that has done better than Walmart, soaring nearly 175%. But since Nvidia just joined the Dow in early November, you could argue that Walmart is truly the index’s top performer in 2024.

The S&P 500 (SNPINDEX: ^GSPC) is on its way to its second straight year of outsized returns. Meanwhile, famed investor Warren Buffett has clearly taken notice of some elevated valuations, selling some of his top holdings and stockpiling cash.

Here are five key things investors need to know to start the trading day: Stock futures changed little Tuesday morning after the S&P 500 and Nasdaq Composite both slid about 0.6% Monday. S&P 500 futures hovered near the flatline while Nasdaq 100 futures grew 0.