I think CMG will retest the breakout location (325-330 price level) by the end of this week (might happen as soon as today).
The reasons are that the current price action mimics the December 4th, 2017 price action, where CMG sold off into the afternoon.
Another reason is that the volume is not significant and that there is no positive news catalyst driving the spike.
The rationale is that this is simply a technical breakout and CMG will resume the downtrend once the shorts have finished covering today.