In trading on Thursday, shares of the iShares S&P Global Infrastructure Index Fund ETF ( IGF) entered into oversold territory, changing hands as low as $35.1662 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 S&P Global Infrastructure Index Fund, the RSI reading has hit 29.2 — by comparison, the RSI reading for the S&P 500 is currently 40.3. A bullish investor could look at IGF's 29.2 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), IGF's low point in its 52 week range is $32.16 per share, with $39.04 as the 52 week high point — that compares with a last trade of $35.28. iShares S&P Global Infrastructure Index Fund shares are currently trading down about 3.3% on the day.