The S&P 500 has gone nowhere in 2015. That is about to change.

The Average Directional Index (ADX)—an indicator that measures trend strength without regard to direction—just hit 15.46, a level that usually precedes big moves. Volatility is also alarmingly low, which is typical before a breakout or pullback.

Bulls and bears are facing off. It’s too early to crown a winner, but expect the market’s next move to be dramatic.