In trading on Monday, shares of the Mortgage REIT Income ETF ( MORT) entered into oversold territory, changing hands as low as $21.751 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 Mortgage REIT Income, the RSI reading has hit 27.3 — by comparison, the RSI reading for the S&P 500 is currently 41.9. A bullish investor could look at MORT's 27.3 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), MORT's low point in its 52 week range is $19.70 per share, with $29.90 as the 52 week high point — that compares with a last trade of $21.76. Mortgage REIT Income shares are currently trading off about 4.1% on the day.