In trading on Friday, shares of the SPDR STOXXEurope 50 ETF ( FEU) entered into oversold territory, changing hands as low as $37.50 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 STOXXEurope 50, the RSI reading has hit 29.5 — by comparison, the RSI reading for the S&P 500 is currently 33.6. A bullish investor could look at FEU'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), FEU's low point in its 52 week range is $34.42 per share, with $40.74 as the 52 week high point — that compares with a last trade of $37.62. SPDR STOXXEurope 50 shares are currently trading down about 0.6% on the day.