Wall Street gave back most of last week's advance on Monday, as a breakdown in U.S.-Iran diplomacy pushed oil and Treasury yields higher and knocked the S&P 500 back from the edge of a record.
The Close
The S&P 500 finished at 7,683.89, down 59.52 points or 0.77%. The Dow Jones Industrial Average fell 347.52 points, or 0.67%, to 51,481.10. The Nasdaq Composite took the worst of it, dropping 248.34 points or 0.92% to 26,820.38, according to Yahoo Finance market data.
The decline erased most of the ground gained last week, a stretch that had carried the S&P 500 to within reach of its all-time high.
Hormuz Talks Stall
The catalyst arrived over the weekend. President Trump rejected an offer from Iran to reopen the Strait of Hormuz and resume negotiations over its nuclear program. Trump told Axios that Tehran's conditions were something Washington might have agreed to about a year ago — a signal that the two sides remain far apart. He said talks would resume this week.
The strait carried roughly one-fifth of the world's seaborne crude and LNG before the conflict began eight months ago, which is why its status moves energy markets directly. Brent crude pushed above $99 a barrel before easing back below $100. West Texas Intermediate November futures settled at $92.79, up 0.41%.
"Geopolitical risk will define the start of the new trading week after a stall in diplomatic progress between the U.S. and Iran over the weekend," Kyle Rodda of Capital.com said.
Bonds Add to the Pressure
The bond market compounded the problem. The 10-year Treasury yield rose six basis points to 5.24%, while the 30-year reached 5.57% — its highest level since 2004. Higher energy costs feeding into an already firm inflation picture left little room for yields to fall.
Federal Reserve Governor Lisa Cook framed the risk directly, saying she expects "to see continued pressure on inflation from the AI build-out … and from the pass-through of higher oil prices."
Defensive corners of the market held up best. Energy and consumer staples outperformed, while communication services and consumer cyclicals led the decline, per Motley Fool sector data.
Single Stocks Do the Damage
Two company stories dominated the tape.
MongoDB tumbled roughly 17% after the database company said CEO Chirantan "CJ" Desai is stepping down immediately to take a senior role at Meta Platforms. The Associated Press put the intraday drop at 18.5%; a midday snapshot from Motley Fool had it at 16.7%.
Nvidia moved the other way, rising about 2% after approving a plan to return up to another $150 billion to shareholders through buybacks — bringing the program's total remaining authorization to $235 billion. Intel and Advanced Micro Devices both fell on artificial intelligence safety concerns.
Gold offered no shelter, falling 3.83% to $4,122.91 an ounce as rising real yields punished the non-yielding metal.
What It Means
Monday's session was a reminder that this market's two pressure points — oil and the long end of the curve — are now linked. An energy shock that would once have been read as a growth risk is instead being read as an inflation risk, and that pushes yields up rather than down. Until the Hormuz question resolves, equities are trading against a bond market that has no obvious reason to rally.
Sources: Yahoo Finance (live market coverage and closing data, September 28, 2026), The Motley Fool (midday market report), Associated Press via BNN Bloomberg, Axios, Capital.com