In trading on Friday, shares of the AMT-Free Short Municipal Index ETF ( SMB) entered into oversold territory, changing hands as low as $17.4501 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 AMT-Free Short Municipal Index, the RSI reading has hit 26.0 — by comparison, the RSI reading for the S&P 500 is currently 57.0. A bullish investor could look at SMB's 26.0 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), SMB's low point in its 52 week range is $17.37 per share, with $17.80 as the 52 week high point — that compares with a last trade of $17.45. AMT-Free Short Municipal Index shares are currently trading off about 0.3% on the day.