In trading on Wednesday, shares of the SPDR Russell 1000 ETF ( ONEK) entered into oversold territory, changing hands as low as $90.21 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 Russell 1000, the RSI reading has hit 28.7 — by comparison, the RSI reading for the S&P 500 is currently 35.8. A bullish investor could look at ONEK's 28.7 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), ONEK's low point in its 52 week range is $76.98 per share, with $94.00 as the 52 week high point — that compares with a last trade of $90.21. SPDR Russell 1000 shares are currently trading off about 0.5% on the day.