In trading on Friday, shares of the Long Municipal Index ETF (MLN) entered into oversold territory, changing hands as low as $19.45 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 Long Municipal Index, the RSI reading has hit 26.4 — by comparison, the RSI reading for the S&P 500 is currently 52.3. A bullish investor could look at MLN's 26.4 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), MLN's low point in its 52 week range is $18.87 per share, with $20.40 as the 52 week high point — that compares with a last trade of $19.46. Long Municipal Index shares are currently trading off about 0.4% on the day.