The decrease in short interest for Ardelyx suggests that investors are becoming more bullish on the stock. This is further supported by the fact that Ardelyx's short interest is lower than the peer group average, indicating a relatively positive sentiment towards the company. Short interest is a critical indicator of market sentiment, and a decrease typically suggests that investors expect the stock price to rise. Therefore, this could lead to a short-term positive impact on Ardelyx's stock price.