In trading on Thursday, shares of the Proshares Short Oil & Gas ETF (DDG) entered into oversold territory, changing hands as low as $30.07 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 Short Oil & Gas, the RSI reading has hit 27.1 — by comparison, the RSI reading for the S&P 500 is currently 69.6.

A bullish investor could look at DDG's 27.1 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), DDG's low point in its 52 week range is $29.79 per share, with $38.97 as the 52 week high point — that compares with a last trade of $30.08. Proshares Short Oil & Gas shares are currently trading down about 1.6% on the day.