In trading on Thursday, shares of the Proshares Ultra DJ-UBS Natural Gas ETF (BOIL) entered into oversold territory, changing hands as low as $38.95 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 Ultra DJ-UBS Natural Gas, the RSI reading has hit 29.7 — by comparison, the RSI reading for the S&P 500 is currently 62.1.

A bullish investor could look at BOIL's 29.7 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), BOIL's low point in its 52 week range is $29.30 per share, with $127.00 as the 52 week high point — that compares with a last trade of $39.95. Proshares Ultra DJ-UBS Natural Gas shares are currently trading off about 3% on the day.