The S&P 500 extended its run of closes above the benchmark 20-day moving average to 60 trading sessions through Tuesday, the longest stretch since 1998, according to market data compiled by analysts. Over the same period, the index has not recorded a 1% move in either direction for 18 sessions and last suffered a 1% decline just before Flag Day. The calm backdrop has coincided with a string of fresh highs, pushing the gauge to a record 6,305 and lifting its momentum measure almost 30% from a year earlier. The technology-heavy Nasdaq 100 has shown even stronger technical resilience, staying above its 20-day moving average for 61 consecutive sessions—the longest run since 1999 and the second-longest in its history. During the 18-day stretch of muted swings, the index notched 12 record closes, while the S&P 500 recorded 10, underscoring the breadth of the rally across large-cap U.S. equities. Similar episodes have been rare. Carson Group calculations cited by strategists show only four prior occasions in the past five decades when the S&P 500 remained above its 20-day average for 60 days or more; the benchmark was up between 20% and 26% a year later and never lower three months later. Some analysts nevertheless caution that the previous comparable streak in the Nasdaq 100 ended in early 1999, ahead of the dot-com crash, highlighting the risk that extended momentum can precede sharp reversals.