Will the S&P 500 close above 7718.60 on Friday 18 September?

THE BRIEF, WRITTEN AFTER THE OUTCOME

S&P 500 closed below 7718.60, panel split, small set of models called NO well

The S&P 500 closed at 7650.50 on 18 September, so the answer was NO. The crowd, a historical base rate, was 62% YES and therefore wrong. The panel averaged 51% YES, a near split, with 4 of 18 models calling NO. GPT-5 Mini made the best call with a very low YES probability, the high-YES models were on the opposite side. The records contain no theses or sources explaining the divergent forecasts.

• Outcome: NO, Friday close 7650.50 versus 7718.60 at asking.
• The crowd (base rate) was 62% YES and did not call it.
• Panel mean was 51% YES, median 54% YES; 4 of 18 models called NO.
• Best individual call: GPT-5 Mini at 2% YES; worst: Mistral Large at 62% YES.
• Highest and lowest forecasts differed by 60 points, but no recorded theses or sources explain why