Buckle Up, Bumpy Road Ahead! (CNBC)

Considering the S&P is up 35% from its bear market low -- and up 5% this month alone – we can’t help but wonder, is the run sustainable?

According to Christopher Zook, CIO of Caz Investments you’d better buckle up; the market could be heading for a 50% retracement. That’s right – 50% of its gains over the last 8 weeks could soon be wiped out.

“There’s a whole lot of money on the sidelines that is worried the train has left the station without them," he explains on Fast Money. In other words they're fearful they’re missing this move.

“After being down last year there’s no way money managers can excuse being down this year and not participating in the rally. So we’re seeing panic buying which leads me to believe the rally is almost finished.”

He also says that history is not with the bulls. Bear market rallies are typically about 8 weeks long and that’s about the current timeline. “This is typical. Everybody starts getting bullish,” right before the next leg down.

If that's the case, what should you do?

“I’d start buying puts or have stops on your trades,” he counsels so when the market turns lower you’re prepared.