AI-Fueled Rally Lifts S&P 500 5.1% in May; Dell Technologies (DELL) Shares Double, Datadog (DDOG) Jumps 87%

The S&P 500 advanced 5.1% in May, powered by a 15.9% surge in information technology stocks even as eight of the 11 sectors declined. Investor enthusiasm for artificial-intelligence infrastructure concentrated gains in chipmakers and software firms. The iShares Semiconductor ETF (SOXX) jumped 23% for the month and has soared 89% in 2026, building on a 40% gain in 2025. The S&P 500 software and services index rose 16.3% in May, reversing a 15.7% year-to-date loss through April, according to LSEG data. Dell Technologies Inc. (DELL) led all S&P 500 members, with shares more than doubling in May after strong earnings, including a 33% surge on May 29. Datadog Inc. (DDOG) soared 87% during the month, highlighting a sharp reversal in software stocks. Microsoft Corp. (MSFT) added 10% in May but remained down 15.7% for the year through April.