Stock markets dipped on Wednesday as climbing crude prices and fresh inflation concerns weighed on investor sentiment, with major averages retreating across the board. The Dow Jones Industrial Average fell 0.53%, the S&P 500 slipped 0.29%, and the tech-heavy Nasdaq Composite lost 0.38%. Among notable movers, Casey's dropped 15.97%, Vulcan Materials declined 2.87%, Alphabet Class A shares slipped 2.78%, and Kimberly-Clark fell 2.78%.

In the so-called Magnificent Seven group, Meta Platforms (NASDAQ: META) rallied 4.69%, while Tesla (NASDAQ: TSLA) edged up 0.38%. On the downside, Nvidia (NASDAQ: NVDA) dipped 0.08%, Microsoft (NASDAQ: MSFT) slipped 0.11%, Apple (NASDAQ: AAPL) declined 0.21%, Amazon (NASDAQ: AMZN) fell 1.83%, and Google (NASDAQ: GOOGL) lost 2.65%.

Oil prices extended their rally as escalating confrontations between the U.S. and Iran fueled worries that Middle East energy supplies could face further disruption. International benchmark Brent crude jumped more than 2%, breaching the $100-per-barrel milestone for the first time since July.

The sustained climb in crude had already put downward pressure on U.S. equities during Tuesday's shortened trading week following the Labor Day holiday. On Tuesday, the Dow dropped 1.2% (its steepest one-day fall in nearly three weeks), the S&P 500 shed 0.6%, and the Nasdaq slipped 0.3%. Crude futures posted gains for a fourth consecutive session.

Adding to geopolitical tensions, the U.S. military destroyed five Iranian vessels carrying crude oil in response to two previous ballistic missile attack attempts on U.S. Navy ships. Tehran subsequently launched missiles toward Jordan and issued warnings to vessels in the Persian Gulf.

Joachim Klement from Panmure Liberum commented: "Oil at $100 brings inflation pressure back into focus. In this environment, with a lack of clear forward guidance from the Fed, Thursday's ECB policy decision and Lagarde's speech become more important. Expect equity markets to adopt a wait-and-see stance today."

As Brent once again touched the key $100 threshold—the last time it hit that mark was in July—a noticeable ripple effect spread across various asset classes. Meanwhile, traders are awaiting Friday's release of the latest U.S. inflation data, widely seen as a deciding factor in whether the Federal Reserve raises interest rates next week. Money markets currently price in roughly a 60% probability of a Fed rate hike.

Fueled by concerns that rising oil prices could aggravate inflation, the yield on the 10-year Treasury briefly touched the closely watched 4.8% level on Tuesday. The uptick in yields further weighed on equity performance that day. Recently, mounting worries over persistently elevated inflation, heavy government borrowing, and a wave of corporate bond issuance have jointly pushed global bond yields to multi-year highs.

The U.S. Treasury is set to auction $39 billion in 10-year notes on Wednesday, following Tuesday's sale of $58 billion in 3-year notes, which saw auction yields hit their highest for that tenor since 2024. The 10-year Treasury yield rose 2 basis points to 4.81%, hovering near levels last seen in 2023.

Traders are also awaiting Thursday's announcement from the Treasury regarding the size of its buyback operations for outstanding 10- and 20-year bonds—part of Treasury Secretary Scott Bessent's efforts to push down U.S. government borrowing costs. Cara Murphy, Chief Investment Officer at Kestrel Investment Management, remarked: "This is a short-term hurdle. There aren't many bright spots to focus on in the current earnings season, so market attention has shifted to various risk factors."

Across European markets, the pan-European Stoxx 600 declined 0.69%, with the UK's FTSE 100 down 0.32%, Germany's DAX off 0.68%, France's CAC 40 down 0.95%, and Italy's FTSE MIB falling 1.27%.

In Asia-Pacific trading, Japan's Nikkei 225 closed 0.19% lower, South Korea's KOSPI gained 1.40%, Australia's S&P/ASX 200 slid 0.11%, and China's CSI 300 finished 0.30% higher.