In trading on Monday, shares of the iShares MSCI Emerging Markets Eastern Europe ETF (ESR) entered into oversold territory, changing hands as low as $17.75 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 iShares MSCI Emerging Markets Eastern Europe, the RSI reading has hit 29.5 — by comparison, the RSI reading for the S&P 500 is currently 38.3. A bullish investor could look at ESR's 29.5 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), ESR's low point in its 52 week range is $14.46 per share, with $25.42 as the 52 week high point — that compares with a last trade of $17.77. iShares MSCI Emerging Markets Eastern Europe shares are currently trading off about 2.1% on the day.