Since the gap up, the stock appears to have formed a type of basing pattern called a "flag." This could be a bullish sign if the stock breaks above this area on high volume.
On June 1st, ACOR gapped up on large volume (>5 Million shares compared to the average trading volume of ~25K shares/day). Institutional sponsorship also was a factor in this move. RSI (the stock's strength indicator) also significantly increased this day making the stock to date one of the stronger stocks in the market.