In trading on Wednesday, shares of the Daily Energy Bull 3x Shares ETF ( ERX) entered into oversold territory, changing hands as low as $52.10 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 Daily Energy Bull 3x Shares, the RSI reading has hit 29.9 — by comparison, the RSI reading for the S&P 500 is currently 57.1. A bullish investor could look at ERX's 29.9 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), ERX's low point in its 52 week range is $52.10 per share, with $135.98 as the 52 week high point — that compares with a last trade of $52.74. Daily Energy Bull 3x Shares shares are currently trading off about 7.2% on the day.