In trading on Monday, shares of the Vanguard FTSE Developed Markets ETF (VEA) entered into oversold territory, changing hands as low as $34.39 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 Vanguard FTSE Developed Markets, the RSI reading has hit 25.9 — by comparison, the RSI reading for the S&P 500 is currently 35.3. A bullish investor could look at VEA's 25.9 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), VEA's low point in its 52 week range is $29.91 per share, with $39.67 as the 52 week high point — that compares with a last trade of $34.44. Vanguard FTSE Developed Markets shares are currently trading down about 2.4% on the day.