In trading on Friday, shares of the Proshares Ultra Nasdaq Biotechnology ETF ( BIB) entered into oversold territory, changing hands as low as $74.88 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 Proshares Ultra Nasdaq Biotechnology, the RSI reading has hit 29.3 — by comparison, the RSI reading for the S&P 500 is currently 53.0. A bullish investor could look at BIB'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), BIB's low point in its 52 week range is $36.45 per share, with $109.74 as the 52 week high point — that compares with a last trade of $75.64. Proshares Ultra Nasdaq Biotechnology shares are currently trading off about 5.5% on the day.