The Globe and Mail reports in its Thursday edition that for years, 5 per cent on the U.S. 10-year Treasury yield was seen as a turbulence threshold. A Reuters dispatch to The Globe reports that this month's 5-per-cent breach has led investors to consider a troubling question: Could 6 per cent be the new figure to worry about? Five per cent has always been a psychological marker rather than an automatic tripwire, says BlueBay Asset's Mike Bell. He says what matters is how Treasury yields compare with other key investment metrics, particularly the earnings yield on stocks. He says that relationship is now approaching an inflection point, potentially setting the stage for an equity sell-off. JP Morgan analysts say one of the reasons why the pain-point might now be above 5 per cent again is a "key structural shift" in the global economy, with artificial intelligence, health care and services playing a bigger role. Many of those firms are spending and expanding, regardless of the level of borrowing costs. JPMorgan says that means "the traditional interest-rate channel looks materially less binding" and the "breaking threshold" of stock markets may be "meaningfully higher, potentially in the 5.5- to 6-per-cent range."