In trading on Wednesday, shares of the Vanguard Long-Term Government Bond ETF ( VGLT) entered into oversold territory, changing hands as low as $78.02 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 Long-Term Government Bond, the RSI reading has hit 25.5 — by comparison, the RSI reading for the S&P 500 is currently 52.1. A bullish investor could look at VGLT's 25.5 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), VGLT's low point in its 52 week range is $73.20 per share, with $87.92 as the 52 week high point — that compares with a last trade of $77.87. Vanguard Long-Term Government Bond shares are currently trading down about 2.5% on the day.