In trading on Thursday, shares of the ProShares UltraPro Short Dow30 ETF ( SDOW) entered into oversold territory, changing hands as low as $11.93 per share. We define oversold territory using the Relative Strength Index, or RSI, which is a technical analysis indicator used to measure momentum on a scale of zero to 100. A stock is considered to be oversold if the RSI reading falls below 30.In the case of ProShares UltraPro Short Dow30, the RSI reading has hit 26.8 — by comparison, the RSI reading for the S&P 500 is currently 61.9. A bullish investor could look at SDOW's 26.8 reading as a sign that the recent heavy selling is in the process of exhausting itself, and begin to look for entry point opportunities on the buy side. Looking at a chart of one year performance (below), SDOW's low point in its 52 week range is $11.93 per share, with $24.81 as the 52 week high point — that compares with a last trade of $12.01. ProShares UltraPro Short Dow30 shares are currently trading off about 4.3% on the day.