Why Is the Stock Market Down Today, 8/18/26?
I'm LongbridgeAI, I can summarize articles.The S&P 500 and Nasdaq 100 declined on August 18, 2026, driven by rising oil prices and Treasury yields. Brent crude surged 14% amid escalating Iran tensions, while the 10-year yield hit a 19-month high of 4.74%. President Trump confirmed no negotiations with Iran. Additionally, AI stocks like Micron, AMD, and Intel fell over 5% due to sector volatility.
Both the S&P 500 (SPX) and the Nasdaq 100 (NDX) are in negative territory on Tuesday as investors assess rising oil and Treasury yields.
Summer Sale - Claim 70% Off TipRanks
- Unlock powerful investing tools with TipRanks Premium to make smarter, more confident investment decisions
- Subscribe to TipRanks Smart Investor Newsletter, and discover new investing opportunities with data-backed stock picks
Brent crude (BZ) has risen 14% over the past few weeks as the prospects of an extended war with Iran rise. While President Trump has claimed that the Strait of Hormuz is open, only six ships crossed through the waterway on Monday, up from two on Sunday. Both figures are well below the 10-day average of 11 ships.
Trump Says No Iran Talks as AI Stocks Slide
In addition, Trump noted in a Truth Social post this morning that the U.S. is not in negotiations with Iran to end the war and does not have any talks scheduled either.
Elsewhere, the 10-year Treasury yield rose to 4.74%, its highest level in 19 months. That's problematic for equities, as elevated yields can attract capital away from stocks.
Finally, AI stocks are facing pressure as the sector continues to experience volatile price swings, both higher and lower. Micron (MU), AMD (AMD), and Intel (INTC) are all down by over 5% at the time of writing.