US stock indexes posted strong gains on June 18, 2026, driven by a semiconductor rally and renewed optimism surrounding a US-Iran peace agreement. The Nasdaq Composite led the advance with a 1.9% increase, while the S&P 500 rose more than 1%.
The Philadelphia Semiconductor Index surged 6.4%, marking the session's standout performance. Intel shares jumped 10.6% to an all-time closing high after President Donald Trump announced a strategic collaboration between Apple and Intel focused on domestic chip design and manufacturing.
Nvidia and Micron also capitalized on the momentum, rising 3.5% and 10.5% respectively. This domestic catalyst converged with a geopolitical breakthrough as the US and Iran signed an interim peace agreement extending their ceasefire by 60 days. Reduced geopolitical risk typically eases inflationary pressure through lower oil prices.
Bitcoin traded above $65,000 in anticipation of the diplomatic deal but experienced a slight pullback as equities rallied. Lingering expectations of potential rate hikes tempered speculative appetite despite the broader risk-on sentiment. The 60-day ceasefire extension provides markets a window of relative calm, potentially offering the Federal Reserve room to pause rate hikes if energy-driven inflation subsides.