In trading on Thursday, shares of the iShares MSCI Emerging Markets Eastern Europe ETF ( ESR) entered into oversold territory, changing hands as low as $22.01 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 28.5 — by comparison, the RSI reading for the S&P 500 is currently 39.8. A bullish investor could look at ESR's 28.5 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 $20.40 per share, with $28.11 as the 52 week high point — that compares with a last trade of $22.01. iShares MSCI Emerging Markets Eastern Europe shares are currently trading down about 1.5% on the day.