In trading on Monday, shares of the iShares Core High Dividend ETF ( HDV) entered into oversold territory, changing hands as low as $73.39 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 Core High Dividend, the RSI reading has hit 29.3 — by comparison, the RSI reading for the S&P 500 is currently 35.1. A bullish investor could look at HDV's 29.3 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), HDV's low point in its 52 week range is $65.45 per share, with $76.57 as the 52 week high point — that compares with a last trade of $73.56. iShares Core High Dividend shares are currently trading down about 0.2% on the day.