In trading on Friday, shares of the Vanguard S&P Small-Cap 600 Growth ETF (VIOG) entered into oversold territory, changing hands as low as $138 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 S&P Small-Cap 600 Growth, the RSI reading has hit 29.7 — by comparison, the RSI reading for the S&P 500 is currently 32.0. A bullish investor could look at VIOG's 29.7 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), VIOG's low point in its 52 week range is $126.674 per share, with $154.03 as the 52 week high point — that compares with a last trade of $140.88. Vanguard S&P Small-Cap 600 Growth shares are currently trading off about 0.1% on the day.