The bull market on Wall Street persists, aided by stocks like Nvidia and Microsoft, which are posting tremendous results on the back of the artificial intelligence (AI) boom. Knowing when to invest with the market near all-time highs is difficult.

Nvidia stock has been on a disappointing run since its earnings last week but the good vibes looked set to return in a holiday-shortened session Friday.

Among the companies benefiting from artificial intelligence (AI) entering the mainstream are semiconductor giants Broadcom ( AVGO -0.11%) and Nvidia ( NVDA -3.10%). The arrival of AI supercharged sales for both businesses as customers sought the necessary hardware and software to implement AI into their organizations.

Analysts have been busy updating their discounted cash flow models and price targets for Nvidia (NVDA) after the most important AI company in the world failed to give the sort of blow-out revenue guidance Wall Street has come to expect.

Additionally, Nvidia's stock is technically cheaper than AMD's. While not inexpensive, Nvidia's shares have a price-to-earnings ratio of 69, which is far cheaper than AMD's stock's P/E ratio of 130.