US equity futures turned negative before the opening bell, erasing earlier gains as investors reassessed the likelihood of a swift resolution to the conflict in Iran. The morning's momentum stalled, reflecting a sudden pullback in risk appetite across Wall Street trading desks.

This shift underscores how directly global geopolitical flashpoints can dictate short-term moves in American capital markets. The initial rebound had presumably priced in some expectation of de-escalation. As that conviction wanes, so too does the immediate demand for assets like stocks, triggering a swift reversal in futures pricing.

The development highlights the market's continued sensitivity to Middle East tensions. For now, the price action suggests a palpable reduction in the 'geopolitical risk premium' traders were previously willing to absorb, leaving the S&P 500's near-term trajectory dependent on renewed diplomatic signals.