In trading on Thursday, shares of the Proshares Short High Yield ETF (SJB) entered into oversold territory, changing hands as low as $29.6942 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 Short High Yield, the RSI reading has hit 29.3 — by comparison, the RSI reading for the S&P 500 is currently 66.6. A bullish investor could look at SJB's 29.3 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), SJB's low point in its 52 week range is $29.51 per share, with $34.00 as the 52 week high point — that compares with a last trade of $29.70. Proshares Short High Yield shares are currently trading down about 0.5% on the day.