Three days of red across every major US stock index, and the culprit is as old as markets themselves: oil.
Brent crude surged to approximately $101 per barrel on September 9, a level not seen since July, dragging the Dow Jones Industrial Average down by 300 to 346 points (roughly 0.6-0.7%). The S&P 500 shed about 0.3-0.5%, while the Nasdaq Composite dropped 0.5-0.7%. All three indices have now declined for three consecutive sessions.
The catalyst behind the oil spike is familiar at this point: escalating tensions between the US and Iran. Reports of tanker strikes and supply route disruptions have rattled energy markets, and crude traders are pricing in the kind of risk premium that makes equity investors very uncomfortable.
The Strait of Hormuz problem
The Strait of Hormuz is a narrow bottleneck through which a substantial portion of global oil exports flow. The US-Iran conflict that’s been simmering since at least February 2026 has repeatedly disrupted confidence in the security of that route. Every report of military activity near the strait sends ripples through crude markets, and those ripples eventually crash into stock portfolios thousands of miles away.
