The most recent short interest data has been released for the 06/30/2017 settlement date, which shows a 265,607 share decrease in total short interest for Martin Marietta Materials, Inc. ( MLM), to 1,846,652, a decrease of 12.57% since 06/15/2017. 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 MLM at the 06/30/2017 settlement increased to 608,556, as compared to 416,942 at the 06/15/2017 report. That brought "days to cover" down to 3.03, a 40.10% decrease from the 5.07 days to cover calculated at the previous short interest data release.The below chart shows the historical "days to cover" for MLM 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 MLM had been shorted as a hedge. The chart below shows the one year performance of MLM shares, versus its 200 day moving average. Looking at this chart, MLM's low point in its 52 week range is $167.06 per share, with $244.32 as the 52 week high point — that compares with a last trade of $225.51. According to the ETF Finder at ETF Channel, MLM makes up 4.71% of the PowerShares Dynamic Building & Construction Portfolio ETF (PKB) which is lower by about 0.2% on the day Thursday.