The S&P 500 could soar more than 20% in the next year after an ultra-rare buy signal just flashed

• An incredibly rare bullish stock market indicator just flashed, suggesting big upside ahead.
• The Zweig Breadth Thrust indicator flashed on Friday after the S&P 500 saw its biggest weekly gain of the year.
• "All you need to know is since WWII, the S&P 500 is higher a year later every time," Ryan Detrick said. 

A rare bullish stock market indicator just flashed, and it's a signal that suggests that the S&P 500's bull market rally that started in October 2022 has more room to go higher.