The Globe and Mail reports in its Saturday edition that combine rising bond yields and AI's questionable economics and the math supporting today's lofty stock prices begins to look shaky. The Globe's Ian McGugan writes that both the S&P 500 and the S&P/TSX Composite Index have barely budged in four months. Investors are nervous. You can see that in the recent rash of delayed U.S. initial public offerings. The anxiety is also evident in declining market breadth. In both Canada and the U.S., a handful of companies are powering most of the market's gains. While broad stock market indexes are still hovering near record highs, the reality for many individual companies is far grimmer. Thirty-eight per cent of S&P/TSX companies and 43 per cent of S&P 500 companies are 20 per cent or more below their 52-week highs. Bond yields, which ultimately determine everything from mortgage rates to what you pay for a car loan, have been on fire in recent months. Five years ago, a 10-year Canada bond was yielding a mere 1.5 per cent, shares of supersafe RBC were paying double that amount in dividends. Now the math has reversed. The 10-year Canada bond is yielding nearly 4 per cent while RBC is paying about 2.5 per cent.