In trading on Friday, shares of the SPDR Blackstone / GSO Senior Loan ETF ( SRLN) entered into oversold territory, changing hands as low as $49.42 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 SPDR Blackstone / GSO Senior Loan, the RSI reading has hit 28.9 — by comparison, the RSI reading for the S&P 500 is currently 34.3. A bullish investor could look at SRLN's 28.9 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), SRLN's low point in its 52 week range is $49.35 per share, with $50.27 as the 52 week high point — that compares with a last trade of $49.57. SPDR Blackstone / GSO Senior Loan shares are currently trading off about 0.2% on the day.