Indeed, the consequences of the latest downgrade seem positively tame by comparison: the last time the US sovereign credit rating was downgraded, the S&P plunged 6.7% with all stocks in the red for the first time since at least 1996, and briefly dropped into a bear market (the benchmark eventually erased those losses five trading days later and is up 282% since). Also, yields tumbled, gold exploded and the SNB was forced to devalue the franc.
Source
https://www.thegatewaypundit.com/2023/08/fitch-ratings-downgrades-u-s-long-term-rating/
https://www.zerohedge.com/markets/market-looking-excuses-take-profits-futures-slide-us-downgrade-shakes-sentiment