President Trump has announced a blockade of the Strait of Hormuz, set to take effect later today, April 18, 2026. The Polymarket contract for the S&P 500 moving down on April 14 is at 100% YES.

Traders expect the blockade will disrupt oil supplies and raise prices, increasing market volatility and pressuring the S&P 500 downward. The April 14 market sits at 100% YES, as does the April 14 opens market, also at 100% YES. Both reflect consensus on a bearish outcome.

Both April 14 prediction markets show no current trading volume, with odds locked at 100% YES. This means thin liquidity could exacerbate price swings when trading resumes.

About 20% of global oil transit passes through the Strait of Hormuz. A disruption at that scale would ripple through energy markets fast. Traders betting on a downturn are watching for Brent crude to surge past $110, which would put further pressure on the S&P 500.

Watch for statements from the Federal Reserve, particularly Powell’s next speech, which could signal monetary policy adjustments in response to the blockade.

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