In trading on Thursday, shares of the iShares Target Date 2040 ETF ( TZV) entered into oversold territory, changing hands as low as $43.932 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 Target Date 2040, the RSI reading has hit 29.5 — by comparison, the RSI reading for the S&P 500 is currently 32.2. A bullish investor could look at TZV's 29.5 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), TZV's low point in its 52 week range is $39.32 per share, with $46.79 as the 52 week high point — that compares with a last trade of $43.93. iShares Target Date 2040 shares are currently trading off about 0.7% on the day.