In trading on Friday, shares of the SPDR Nuveen S&P High Yield Municipal Bond ETF ( HYMB) entered into oversold territory, changing hands as low as $56.34 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 Nuveen S&P High Yield Municipal Bond, the RSI reading has hit 26.9 — by comparison, the RSI reading for the S&P 500 is currently 53.4. A bullish investor could look at HYMB's 26.9 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), HYMB's low point in its 52 week range is $54.31 per share, with $59.07 as the 52 week high point — that compares with a last trade of $56.45. SPDR Nuveen S&P High Yield Municipal Bond shares are currently trading off about 1% on the day.