Nvidia (NASDAQ: NVDA) stock is falling in Tuesday's trading. The artificial intelligence (AI) leader's share price was down 5.5% as of 2:45 p.m. ET amid a 0.9% decline for the S&P 500 index and a 1.6% pullback for the Nasdaq Composite index.

Chipmaker and AI darling Nvidia is back nipping at Apple's heels as the most valuable company in the world, with the stock hitting an all-time high Monday.

NVIDIA (NASDAQ: NVDA) is still the most important stock after two-plus years of dominating the stock market. Its GPU technology unlocked the door to AI, and now NVIDIA is capitalizing on it using a full-stack method.

This top artificial intelligence (AI) stock trades close to its all-time high, as of this writing. After such an incredible run, should you still consider buying Nvidia right now? Nvidia sells graphics processing units (GPUs) that provide computing power for various uses.

Investors are always scanning the horizon for the next big thing in stocks. For the past few years, it's clear that Nvidia (NASDAQ: NVDA) has been the key winner that's driven most index (and portfolio) returns.