One force is propping up the economy. Fears are growing it won’t last

San Francisco - Spending by consumers has dominated the American economy for decades, usually the largest driver of economic growth. But in the first half of this year, spending by companies on artificial intelligence rivaled consumers as the primary engine of the nation’s economic expansion.

That startling shift is one of many recent examples of AI’s increasingly outsize role in propping up U.S. economic fortunes - and a sign, some fear, of a soon-to-pop speculative bubble that could cause widespread financial pain.