The most recent short interest data has been released by the NASDAQ for the 05/15/2015 settlement date, which shows a 347,194 share decrease in total short interest for Imperva Inc. ( IMPV), to 1,583,660, a decrease of 17.98% since 04/30/2015. Total short interest is just one way to look at short data; another metric that we here at Dividend Channel find particularly useful is the "days to cover" metric because it considers both the total shares short and the average daily volume of shares traded. The number of shares short is then compared to the average daily volume, in order to calculate the total number of trading days (at the average volume) it would take to close out all of the open short positions if every share traded represented a short position being closed. Average daily volume for IMPV at the 05/15/2015 settlement increased to 706,001, as compared to 326,975 at the 04/30/2015 report. That brought "days to cover" down to 2.24, a 62.01% decrease from the 5.91 days to cover calculated at the previous short interest data release.The below chart shows the historical "days to cover" for IMPV at previous short interest release dates: A decreased "days to cover" value could indicate that short sellers are no longer expecting the same decline in stock price they once were, or it could also indicate a long bet elsewhere was closed where IMPV had been shorted as a hedge. The chart below shows the one year performance of IMPV shares, versus its 200 day moving average. Looking at this chart, IMPV's low point in its 52 week range is $19.09 per share, with $61.69 as the 52 week high point — that compares with a last trade of $60.83.