Apple, Microsoft, and 3 other stocks are now worth nearly $9 trillion – or almost 25% of the S&P 500

• The five biggest stocks on the S&P 500 are now worth nearly $9 trillion - or almost 25% of the benchmark index.
• Those companies include Apple, Microsoft, Alphabet, Amazon, and Nvidia.
• Tech stocks have staged an impressive rally this year as hype around AI lifts industry stocks.

The five biggest S&P 500 companies have a combined market capitalization worth nearly $9 trillion - or almost 25% of the benchmark index.

The top companies include tech giants Apple, Microsoft, Alphabet, Amazon and Nvidia, TheBoomBust.com first reported on Twitter.

Tech stocks have had a smashing start to the year thanks to the hype around artificial intelligence, following the launch of OpenAI's ChatGPT.

Excitement around AI has not only seen a tech war breakout among industry giants including Microsoft, Alphabet and Meta to lead the AI boom, but also a flurry of investors parking their money in stocks best able to take advantage of the AI revolution.

Nvidia has specifically enjoyed the ride to the top, with the Santa Clara-based chipmaker's stock surging 116.55% since the start of 2023, making it the best-performing stock of the year on the S&P 500. The company has a market cap of $773 billion.

Investors see Nvidia as well-positioned to take advantage of the AI boom, given its the No.1 producer of graphic chips needed for high-intensity computing.

With AI in the limelight, it's drawn a pool of both bulls and bears. While billionaire investor Paul Tudor Jones said the technology could spur a productivity boom, Bank of America's top strategist has warned of trouble ahead for the tech sector.

In a recent interview on CNBC, BofA's Savita Subramanian said investors should shun mega-cap tech stocks as a "big asset bubble" is building in growth shares.

"You don't want to buy mega-cap tech. That's old leadership," Subramanian said, adding that tech is showing its cyclicality in today's environment.