Nvidia has led the S&P 500 ( ^GSPC -0.29%) higher this year amid frenetic interest in artificial intelligence (AI). The stock has surged 136% since January, and Wall Street analysts forecast median upside of 30% from the current share price of $115. But betting on a single AI stock is a bad strategy.

The central bank's decision to slash borrowing costs by 50 basis points is easing concerns about the economy. That could lift the AI trade.