The underlying strength of the continuous rise in U.S. stocks: The S&P 500 profit margin has hit a historic record of 16.9%, and its not just reliant on the "big tech's solo performance" as 80% of industry profit margins are rising together.

According to Smart Financial APP, the ratio of retained earnings per $1 of sales for S&P 500 companies has reached a historical high, adding another tailwind for the upward trend of U.S. stocks. John Bartus, Senior Earnings Analyst and Vice President at FactSet, stated based on FactSet's data that the blended net profit margin of the S&P 500 index in the second quarter has risen to 16.9%, significantly higher than the 14.8% in the first quarter and 12.9% from the same period last year, and far above the five-year average of 12.4%.