In trading on Wednesday, shares of the Guggenheim BulletShares 2020 Corporate Bond ETF ( BSCK) entered into oversold territory, changing hands as low as $21.16 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 2020 Corporate Bond, the RSI reading has hit 29.8 — by comparison, the RSI reading for the S&P 500 is currently 54.1. A bullish investor could look at BSCK's 29.8 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), BSCK's low point in its 52 week range is $20.91 per share, with $22.29 as the 52 week high point — that compares with a last trade of $21.17. Guggenheim BulletShares 2020 Corporate Bond shares are currently trading off about 0.5% on the day.