A broad technology selloff extended into a second day Tuesday, with investors questioning whether artificial intelligence investments will deliver the profits that have supported high valuations at firms including Alphabet, SpaceX and Nvidia.

Following the opening bell, the tech-focused Nasdaq Composite fell 628 points, or 2.4 percent, to 25,537. The index posted its second consecutive decline after dropping 1.3 percent on Monday.

The Dow Jones Industrial Average eased 305 points, or 0.6 percent, to 51,407, while the S and P 500 declined 1.6 percent.

Wall Street had favored technology shares for months, lifting markets to record levels on hopes that heavy AI spending would yield faster revenue growth and stronger earnings. Market participants now seek clearer signs that those outlays will succeed.

Several leading technology names that had driven the rally faced renewed selling pressure amid rising doubts.

Nigel Green, chief executive of financial consultancy deVere Group, noted in an email that investors had long viewed AI spending as an unqualified positive. He added that market participants are now insisting on tangible results from the record levels of investment.

SpaceX shares fell 4.09 dollars, or 2.7 percent, to 150.51 after a 16 percent drop on Monday. The stock had surged past 200 dollars shortly after its initial public offering earlier in the month but has now declined for four straight sessions as concerns mount over its valuation exceeding 2 trillion dollars.

Bret Kenwell, a U.S. investment and options analyst at eToro, told CBS News that wider weakness and global volatility in technology shares are pressuring U.S. equities. Nvidia declined 3.4 percent and Broadcom lost 2.4 percent on Tuesday.

Alphabet, a member of the Magnificent Seven group, also retreated, falling 1.2 percent in early trading.

Green stated that the current pullback does not signal broader market distress. He described the shift toward demanding evidence rather than assurances as uncomfortable yet ultimately constructive for investors.