In trading on Thursday, shares of the Guggenheim BulletShares 2018 High Yield Corporate Bond ETF ( BSJI) entered into oversold territory, changing hands as low as $26.26 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 Guggenheim BulletShares 2018 High Yield Corporate Bond, the RSI reading has hit 29.6 — by comparison, the RSI reading for the S&P 500 is currently 65.3. A bullish investor could look at BSJI's 29.6 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), BSJI's low point in its 52 week range is $26.09 per share, with $27.49 as the 52 week high point — that compares with a last trade of $26.28. Guggenheim BulletShares 2018 High Yield Corporate Bond shares are currently trading off about 0.2% on the day.