US and European stocks sputtered Thursday as investors weighed another wave of corporate results, interest rates, the US government shutdown and a Supreme Court hearing on President Donald Trump's tariffs.

Wall Street's tech-heavy Nasdaq and broad-based S&P 500 opened lower, retreating from gains in the previous day after fears of an AI bubble shook the markets earlier this week.

Asian markets closed higher but Europe's main indexes were down in afternoon deals.

"The week began with doubts cast over the future returns on investments made in Artificial General Intelligence (AGI)," said David Morrison, analyst at Trade Nation.

"Not only are the sums involved quite mind-boggling, but there are also concerns over the circularity of much of the investment," he said.

The more than month-lon

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