Wall Street experienced a sharp selloff on May 15, 2026, as investors dumped semiconductor companies and high-flying tech stocks, halting a weeks-long record-setting rally fueled by AI optimism and megacap gains [1]. The S&P 500 Index fell 1.2%, and the Nasdaq 100 declined 1.5%, marking their worst trading day since late March [1].

The tech rally in 2026 has been driven mainly by a small group of megacap AI and hyperscaler stocks, which accounted for more than half the S&P 500 gains so far this year [2]. However, concerns about rising bond yields weighed on the sector. The Philadelphia Semiconductor Index (SOX) trades at more than 25 times forward earnings, well above its decade average of 19, raising valuation concerns [2].

A key focus for investors is the 30-year US Treasury yield, which recently surpassed 5%. Many regard this level as a "danger zone" that threatens to slow or reverse the tech stock rally. "The yield on 30-year US Treasuries holding sustainably above 5 per cent is the 'danger zone' for stocks," said Alexandre Drabowicz, chief investment officer at Indosuez Wealth Management [2].

Despite yield worries, investors remain broadly optimistic on technology and AI. A Bloomberg survey of 32 investment managers found 80% expect equities to outperform other asset classes like bonds and commodities over the next three to six months [3, 2]. Raphael Thuin, head of capital market strategies at Tikehau, said, "We continue to see opportunities in some of the hyperscalers, which have led the AI build-out and are now beginning to generate tangible returns on their investments" [2].

The selloff on May 15 reflected profit-taking and caution around elevated valuations amid higher interest rates, rather than a broad loss of confidence in tech innovation and AI growth prospects. Investors are weighing short-term risks from bond yields against longer-term earnings potential in hyperscale companies heavily involved in AI [2].

Markets will watch how long US Treasury yields stay above 5% and whether earnings reports from major tech firms confirm the sustainability of AI-driven growth. The next key test will come as companies report second-quarter results in July and August.