European shares fell in the session as reports of an Iranian plan to restrict the Hormuz shipping zone unsettled traders already bracing for an expected European Central Bank rate hike. The FTSE 100 slipped as the US-Iran Gulf conflict escalated, according to wire reports, and Novartis shares were among the decliners on the broader European market.

Oil prices did the heavy lifting on the downside for stocks. Brent crude was overbought at $97 with a Relative Strength Index reading of 74 on an hourly chart, a level technical traders treat as stretched. WTI crude sat just under a double-top resistance level at $93.64. Higher energy costs squeeze corporate margins and household spending, which is why equity markets moved lower even without a direct hit to any single company's earnings.

What remains unresolved is whether the Hormuz plan translates into an actual disruption of tanker traffic through the strait, which carries a large share of global seaborne oil. Until that clarifies, oil's overbought technical readings and Europe's equity weakness are likely to track each other closely.