AI Investment Craze Dominates Structural Rally in US Stocks: Nasdaq, Philadelphia Semiconductor Index Hit New Record Highs, Micron Technology Joins Trillion-Dollar Club

Tradingkey - On May 26, 2026, Eastern Time (the first trading day after the Memorial Day holiday), the three major U.S. stock indices continued their overall upward trajectory, driven by the dual factors of the intensifying AI investment craze and easing geopolitical risks from expectations of a U.S.-Iran peace agreement. The Nasdaq Composite and S&P 500 both refreshed record highs: the Nasdaq touched an intraday peak of 26,725.29 points, while the S&P 500 reached an intraday high of 7,539.09 points; the Dow Jones Industrial Average, however, opened higher before trending lower, declining 0.16% as of press time.

Market analysis suggests the U.S. economy is still expanding, but consumer divergence is evident, with discount retail performing better. The EIA expects crude oil supply and demand to balance only by Q1 2027; high oil prices and secondary inflation will continue to impact corporate operations, which, combined with the waning effects of tax rebates in the second half of the year, means the K-shaped phenomenon will be difficult to mitigate. S&P 500 blue-chips and AI companies led Q1 earnings, with the structural uptrend continuing and expanding to mid- and small-cap indices; the AI supply chain remains the primary trading theme.

On the latest geopolitical front, the U.S. Navy has begun resuming the guidance of vessels through the Strait of Hormuz. According to The Wall Street Journal, U.S. military officials revealed that the Navy has resumed assisting ships transiting the strait. Officials said a Greek supertanker carrying 2 million barrels of crude received a naval escort while passing through waters off the coast of Oman. The vessel had been stranded in the Gulf since early March and is now bound for India. The escort marks the restart of 'Operation Freedom'.

At the sector level, the AI industrial chain became the clear leader, with the Philadelphia Semiconductor Index driving the day's market movement. The index rose over 5% intraday to a record 12,903.19 points, with memory chips, GPUs, and advanced packaging stocks leading the gains.

Among individual stocks, Micron Technology ( MU) surpassed a $1 trillion market capitalization for the first time, following a rapid rally that solidified its status as a prominent winner in the AI boom as the largest U.S. memory chipmaker.

Micron shares were last up over 16% at $872.24, hitting an intraday record of $891.27. UBS recently hiked its price target from $535 to $1,625, the highest among 46 brokerages tracked by LSEG.

Long seen as a highly cyclical player in semiconductors, Micron's stock has surged roughly eightfold in the past 12 months, fueled by strong earnings and pricing power from supply constraints.

Micron previously stated its 2026 supply of High Bandwidth Memory (HBM) chips is sold out, indicating demand significantly outstrips capacity. Its next-gen HBM4 is already in production.

TrendForce noted the Fab 6 expansion is primarily an internal capacity adjustment rather than a return to consumer DDR4 supply. The firm expects Fab 6 wafer starts to reach 1.5 times Q2 2026 levels by Q4 2027, with 1α nm products hitting mass production in late 2026 and quadrupling in scale by 2027.