The Globe and Mail reports in its Saturday edition that it is difficult to pin the recent market euphoria on expectations of lower interest rates. The Globe's Ian McGugan writes that if anything, events seem to be moving in the opposite direction: Stock markets are hitting record highs just as central bankers are talking tough about interest rates and futures markets are dampening their hopes for early rate cuts. One theory is that investors are eager to buy shares because they are excited -- perhaps overexcited -- about the potential of artificial intelligence to reshape the economy. Goldman Sachs analysts argue that AI has the potential to boost global economic output by 10 per cent or more over the decade ahead. Shares of Nvidia, a maker of AI chips, have more than tripled in value over the past year. The hope for some is that AI and other new technologies "will lead to a sustained productivity boom akin to that in the 1960s or late 1990s." Maybe that will happen. Apple and Tesla shares have been down lately. Nervous investors may want to keep a close eye on the diverging course of the Magnificent Seven (Alphabet, Amazon, Apple, Meta, Microsoft, Nvidia and Tesla) as this unusual bull market moves forward.