Stock Market Today, Aug. 31: Stocks Edge Lower as Oil Prices Surge Again

U.S. equities sold off August 31, 2026, as crude oil breached $90 per barrel on escalating U.S.-Iran military tensions. The S&P 500 dropped 0.33%, the Dow Jones fell 0.70%, and the Nasdaq declined 0.12%. Energy stocks rallied on the oil spike while basic materials and industrials led losses.

Despite the daily retreat, the S&P 500 posted a 2.6% gain for August. The session's risk-off tone reflects concern that elevated energy prices will prolong inflationary pressure and reinforce the case for Federal Reserve tightening. Markets are positioning ahead of a potential rate hike at the September FOMC meeting.

The oil surge compounds the Fed's inflation challenge as geopolitical risk premiums return to crude markets. Higher energy costs threaten to reignite headline inflation readings just as core measures have begun to stabilize, potentially forcing the central bank to maintain its restrictive stance longer than investors anticipated earlier in the summer.