Share prices across the US tech sector have rocketed in the past year. Demand for Nvidia and Microsoft shares, for instance, has soared as their pioneering work in the field of artificial intelligence (AI) has delivered blockbuster results. It’s clear that the AI market has room for significant growth. And as an investor I’m looking for ways to capitalise on this and make a life-changing financial return. My concern is that some of these Nasdaq-listed giants look pretty expensive despite this bright outlook. Nvidia shares, for instance, trade on an enormous forward price-to-earnings (P/E) ratio of 73.2 times. And the firm’s price-to-book (P/B) ratio stands at a eye-popping 50 times! Buying these tech stars at these prices is especially unappealing given that we’re so early on in the AI revolution. While we can all have a good guess, at this stage it’s tough to predict which of these companies will succeed. Sophie Lund-Yates, equity analyst at Hargreaves Lansdown, alluded to this last week. When praising Microsoft’s strong first-quarter results, she said: “While Microsoft is top dog, there are other companies snapping at its heels. None are close enough to take much of a bite just yet, but never say never....