In trading on Friday, shares of the iShares International Preferred Stock ETF ( IPFF) entered into oversold territory, changing hands as low as $19.797 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 International Preferred Stock, the RSI reading has hit 27.2 — by comparison, the RSI reading for the S&P 500 is currently 50.8. A bullish investor could look at IPFF's 27.2 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), IPFF's low point in its 52 week range is $19.73 per share, with $25.60 as the 52 week high point — that compares with a last trade of $19.97. iShares International Preferred Stock shares are currently trading off about 1.3% on the day.