The S&P 500 has never been this concentrated in just 2 stocks

Apple ( AAPL ) and Nvidia ( NVDA ) have truly become the straws that stir the stock market's drink.

The S&P 500 ( ^GSPC ) has never been more concentrated in just two stocks than it is today, Creative Planning president Peter Mallouk pointed out. Nvidia and Apple represent over 15% of the index (see chart below).

That percentage dusts the 9.1% concentration seen for Microsoft ( MSFT ) and General Electric ( GE ) in the lead-up to the dot-com bust.

Nvidia and Apple are on quite a run, which helps to explain their rising importance to the S&P 500.

Apple stock hit $345 on Tuesday, marking an all-time high for the iPhone maker's shares. The stock has come slightly off its highs amid a broader market pullback on rising 10-year US Treasury yields .

The stock has been on a sizzling run since Apple unveiled the iPhone 18 and its first foldable, the Duo, earlier this month, pushing the year-to-date gain to 25%.

Nvidia said in late August that its business stands to grow at least 70% in its next fiscal year. If not for supply constraints, CEO Jensen Huang said growth would be north of 100%.

Shares of the chip giant are up 21% year to date.

Brian Sozzi is Yahoo Finance's Executive Editor, host of the Power Players with Brian Sozzi podcast, and a member of Yahoo Finance's editorial leadership team. Follow Sozzi on X @BrianSozzi , Instagram , and LinkedIn . Tips on stories? Email brian.sozzi@yahoofinance.com.