New Delhi, Oct. 14 -- AI stocks have provided the juice for this bull market, which just turned four. Expectations for strong tech earnings, combined with far more reasonable valuations than just a few months ago, could push the market even higher-despite worries about concentration risk.

"The fingerprints of the AI trade are everywhere," said Nicholas Colas, co-founder of DataTrek Research, in a report Tuesday. But the question now is whether investors should continue to bet on AI or start looking elsewhere.

Concentration is a clear concern for anyone primarily investing in the market-cap weighted S&P 500, with the top 10 stocks making up about 40% of the index. And most of those stocks are inextricably linked to AI; it's the Magnifice...