How a US-Iran Truce Sparked a Market Rally and a Chip Sector Rout

Equities seized on the lower oil prices and reduced geopolitical risk. The Dow Jones Industrial Average rallied roughly 260 points, or about 0.6-0.7%, for its second straight gain . S&P 500 and Nasdaq futures were even more exuberant in pre-market trading, jumping 1% and 1.6% respectively, though the session turned more mixed as the day wore on . Buying was broad-based, with most sectoral indices in positive territory, reflecting a relief that the threat of a wider Middle East conflict and supply disruptions through the Strait of Hormuz had receded . U.S. Ambassador to the United Nations Mike Waltz said President Donald Trump had decided to pause military action to pursue a diplomatic path .

Investors, however, quickly priced in that the truce was fragile. The Houthis attacked oil facilities in Saudi Arabia, and Ukraine struck an Iranian commercial vessel in the Caspian Sea over the same weekend . Yet the overarching market narrative on Monday was one of relief.

The Chip Rout: When AI Spending Fears Undermine the Rally

By Tuesday, July 28, the market's mood had shifted dramatically. The broad-based rally gave way to a global semiconductor rout that exposed the deep fault lines in the bull market. The iShares Semiconductor ETF (SOXX) dropped more than 3% in pre-market trading, and the Nasdaq futures turned negative . Nvidia shares shed 5%, and Asian chip markets were hit even harder, with South Korea's KOSPI falling to a three-month low .

What triggered the selloff? A confluence of valuation anxiety and a reckoning with the capital demands of the AI boom. The Wall Street Journal reported that Nvidia was in talks to provide roughly $250 billion in financing guarantees for an Ohio data center project . This staggering figure crystallized growing unease about whether the massive outlays for AI infrastructure — chips, data centers, and energy — would deliver commensurate returns. Reports of rising Chinese competition in the AI chip space added another layer of pressure . The result was a stark divergence: the Dow, buoyed by lower oil and defensive sectors, held up relatively well, while the Nasdaq and Asian markets, dominated by high-flying semiconductor stocks, slumped .

Cross-Asset Dynamics: What Lower Oil Did and Didn't Do

The July 27-28 period offered a masterclass in cross-asset behavior during a geopolitical and tech-driven shock. Crude oil continued sliding on Tuesday as the Iran truce held, with Brent crude falling further toward $87 . But importantly, the lower oil price did not translate into a broad bond rally. Treasury yields remained broadly steady, signaling that markets were not treating the oil decline as sufficiently disinflationary to change expectations for Federal Reserve policy . The U.S. dollar was broadly softer, reflecting reduced geopolitical risk appetite and positioning ahead of the Fed's rate decision .

Asian markets bore the brunt of the chip-led risk-off move, falling sharply on Tuesday, while U.S. and European markets held up relatively better as lower oil prices helped non-tech sectors, including materials and industrials . The unusual split — the Dow up, the Nasdaq down — illustrated a rotational shift rather than a systemic panic, but it underscored the technology sector's vulnerability to capital spending fatigue.

Economic Risks and the Fed's "Live" Meeting

Amid the market turbulence, a hawkish shadow loomed over the week: the Federal Reserve's interest-rate decision on July 29. According to multiple reports, markets were pricing in a 38% probability of a rate hike, an unusually high figure for what many had expected to be a more patient Fed . Saxo Bank described the meeting as "live" and noted that traders were on edge about the possibility of a surprise . This elevated rate hike risk was a significant factor behind the cautious mood, particularly for growth-sensitive tech and chip stocks.

The economic backdrop was already uncertain. The S&P 500 and Nasdaq had fallen for two consecutive weeks heading into this period . The second-quarter earnings season was delivering mixed signals, with an upbeat start from some sectors but persistent weakness in chip stocks that had already been under pressure . The AI spending narrative faced an existential question: Can the massive capital outlays for chips and data centers generate returns, or is the market over-invested? .

The Big Tech Earnings Gauntlet

The week of July 27-31 was widely described as the busiest of the earnings season and one of the most consequential Fed weeks of 2026 . The stakes for the AI trade were highest during this stretch, as investors awaited results from the megacap tech companies whose spending was the rationale for the entire semiconductor rally .

Alphabet had already reported and disappointed, weighing on sentiment going into the week . The upcoming lineup included:

• Federal Reserve rate decision (July 29): 38% probability of a hike priced; markets on edge for any hawkish surprise
• Microsoft earnings: First of the Big Tech megacaps; sets tone for AI spending and cloud growth
• Meta earnings: Key test of AI monetization thesis and digital advertising demand
• Amazon earnings: Consumer and cloud bellwether
• Apple earnings: Largest market cap; signals iPhone demand and AI integration progress

The central tension was clear: lower oil and geopolitical détente were positive for the broad economy and non-tech sectors, but AI capex fatigue, Chinese competition, and a hawkish Fed risk slammed the very sector that had led the bull market. This set up a pivotal test — the Big Tech earnings and Fed decision would determine whether the chip rout was a rotational correction or the start of a deeper unwind .