The Globe and Mail reports in its Thursday, June 4, edition that the rise in U.S. technology stocks has made broader indexes heavily reliant on this sector, increasing vulnerability if these leaders falter. A Reuters dispatch to The Globe reports that the S&P 500 technology sector now makes up over 39 per cent of the benchmark's market cap, its highest on record and surpassing the 2000 Internet bubble level. Miller Tabak analyst Matthew Maley says: "If the small number of tech stocks that have been leading this market higher roll over, by definition, the indexes are going to roll over. And when the indexes roll over in a meaningful way, the money flows inevitably reverse." The expected surge in artificial intelligence use has boosted profit estimates and shares of semiconductor and tech companies. Schwab analyst Liz Sonders says, "There is clearly an overarching AI theme to what is working." Tech has dominated the S&P 500, with a recent 47-per-cent surge since March, outpacing the S&P's overall gains, driven by semiconductors. Micron shares soared 230 per cent, while Intel and AMD rose over 160 per cent. Investors are wary of some sort of trigger that could undercut the AI narrative.