This post ties in with my last SPX daily post illustrating an Elliott wave Ending Diagonal Triangle(EDT) from 2/11/16. Each wave of an EDT subdivides into a three wave pattern. Sometimes the sub waves within the three wave pattern can themselves by divided into a three wave pattern. This is referred to as a Double Zigzag. See "Elliott Wave Principle" pages 42-44.
The move up from the 12/30/16 bottom counts best as a Double Zigzag. If this count is correct it is the completion of a fifth wave up from 11/4/16 and represents the end of the EDT. This count is valid if the SPX does not exceed 2285.92.