Despite the widespread interest AI has generated, it does not yet appear to have led to a valuation bubble, which makes it different, at least for now, from previous narrative investment cycles such as the Internet in the late 1990s. 

If you compare the current valuations of AI-led companies to other periods, they are less at risk of a valuation bubble. Current valuations are well below levels typical of other recent bubbles, dating back to the Nifty 50 era in the early 1970s, the Japanese bubble in the late 1980s, and the technology bubble in 2000. 

For example, the median P/E and enterprise value/sales ratios of the seven largest tech companies (ranked by market capitalization) today are about half of what they were at the peak of the tech bubble in 2000. 

What's more, today's dominant companies are more profitable and have stronger balance sheets than those during the tech bubble.