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Jun 16, 2026 8:00 AM

Stock Market: Will S&P 500 Open Up Or Down Today?

The S&P 500 surged on Monday after President Donald Trump announced a deal to end the war between the U.S. and Iran, but Polymarket traders remain divided on whether the benchmark index can extend its gains at Tuesday’s open.

The S&P 500 jumped 1.65% to close at 7,554.29 on Monday, its strongest daily gain in weeks, as falling oil prices and easing geopolitical tensions boosted risk appetite. The June 16 Polymarket contract implied a 52% probability that the index will open higher on Tuesday, reflecting an almost even split among traders.

Why That Number Matters

Markets rallied after Trump announced that the U.S. and Iran had reached an agreement to end the conflict in the Middle East.

According to ...