RE: Have you ever seen a support level that has supported anything?

 "if a key support level breaks to the downside, it could trigger so-called “negative gamma,” pushing markets lower in a material way... "

support levels are marked by early December lows for all three indexes — 

4,513 for the S&P 500, 

15,085 for the Nasdaq and 

2,130 for the Russell 2000. 

MarketWatch 20 December 2021

https://www.marketwatch.com/story/these-are-the-big-levels-to-watch-for-the-s-p-500-and-nasdaq-expect-wild-trade-if-they-break-warns-this-strategist-11640002294