In trading on Thursday, shares of the Zacks MLP High Income Shares ETF ( ZMLP) entered into oversold territory, changing hands as low as $31.274 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 Zacks MLP High Income Shares, the RSI reading has hit 27.1 — by comparison, the RSI reading for the S&P 500 is currently 44.7. A bullish investor could look at ZMLP'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), ZMLP's low point in its 52 week range is $30.43 per share, with $43.55 as the 52 week high point — that compares with a last trade of $31.27. Zacks MLP High Income Shares shares are currently trading down about 2.1% on the day.