OUTCOME: YES

The S&P 500 closed higher on Tuesday 20 October 2026 than on Friday 16 October 2026. My adjudicated closing levels are **7,712.57** and **7,659.44**, respectively: an increase of **53.13 index points**, approximately **0.694%**. This satisfies the strict-greater-than rule (outcome code 1). This is an expert judgment from the evidence below; direct verification of Tuesday’s close on S&P DJI’s website remains a limitation.

Research was conducted on 20 October 2026, approximately 21:36–21:38 UTC, after the stated 21:30 UTC deadline. I interpret the question as referring to the USD S&P 500 price index, excluding dividends, rather than a total-return index, ETF or futures contract. This interpretation is consistent with [FRED’s description of the S&P DJI series](https://fred.stlouisfed.org/series/SP500).

Evidence and attribution

| Session | Level used | Evidence observed |
| --- | ---: | --- |
| Friday, 2026-10-16 | 7,659.44 | [FRED, S&P 500 (SP500)](https://fred.stlouisfed.org/series/SP500) explicitly lists this date and value, identifies S&P Dow Jones Indices LLC as its source, and describes the observations as daily market closes. [Investing.com’s historical table](https://ca.investing.com/indices/us-spx-500-historical-data) independently displays the same date and level. |
| Tuesday, 2026-10-20 | 7,712.57 | [Associated Press, “How major US stock indexes fared Tuesday 10/20/2026”](https://apnews.com/article/0a5ea168499c6ae617c49e10bf48f9c6), published at 20:25:06 UTC according to the retrieved search result, reports this closing level and a daily gain of 21.84 points. [MarketScreener’s S&P 500 overview](https://www.marketscreener.com/quote/index/S-P-500-4985/) directly displays 7,712.57 with “Market Closed” and a 2026-10-20 16:45:45 EDT timestamp. |

The AP report was available in the search retrieval, but opening its article directly failed. MarketScreener’s page was opened successfully; its separate after-hours field was excluded. AP also reports a week-to-date increase of 53.13 points, consistent with the Friday-to-Tuesday subtraction. These are corroborating observations, not proof that the vendors use independent upstream feeds.

Session validity

The [NYSE holiday and trading-hours calendar](https://www.nyse.com/trade/hours-calendars) lists neither October 16 nor October 20 as a holiday and gives the regular core session as 09:30–16:00 ET. A calendar alone cannot exclude an emergency cancellation. However, the date-specific historical data and Tuesday’s post-close reporting provide affirmative evidence that trading occurred on both dates. I find no basis for the rule-defined INVALID outcome.

Source conflicts, uncertainty and unanswered questions

The named primary source, [S&P DJI’s S&P 500 page](https://www.spglobal.com/spdji/en/indices/equity/sp-500/), was consulted, but the retrieved page did not expose either requested closing level. Its [Daily Index Insights dated October 20](https://www.spglobal.com/spdji/en/commentary/article/daily-index-insights/) discusses the previous session, so it cannot verify Tuesday’s close. FRED supplies S&P DJI-attributed Friday data, but its latest observation at retrieval was October 19. **I did not directly obtain S&P DJI’s official October 20 close and do not claim full completion of that primary-source verification.**

Investing.com’s opened historical table instead showed **7,712.76** for October 20, with a “real-time derived” label and a 15:59:58 closed quote. That is 0.19 points above the AP/MarketScreener level. I prefer 7,712.57 because the explicit post-session news report agrees with the dated market-closed aggregator display. The cause of the discrepancy is unverified; neither a correction nor a particular feed issue is established. Both candidates exceed Friday’s level by over 53 points, so this observed conflict does not change the binary judgment.

Some search results and opened quote pages also returned different intraday snapshots. I excluded values explicitly timestamped before the regular close. The unresolved question is the exact final or subsequently corrected October 20 level in S&P DJI’s own publication. Confidence in YES is high on the available post-close evidence, with lower confidence in having authenticated the exact official closing number. Missing primary-source access is not treated as cancellation or as an additional INVALID condition.