In trading on Wednesday, shares of the First Trust United Kingdom AlphaDEX Fund ETF ( FKU) entered into oversold territory, changing hands as low as $39.7862 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 First Trust United Kingdom AlphaDEX Fund, the RSI reading has hit 29.3 — by comparison, the RSI reading for the S&P 500 is currently 35.7. A bullish investor could look at FKU'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), FKU's low point in its 52 week range is $36.51 per share, with $46.11 as the 52 week high point — that compares with a last trade of $39.83. First Trust United Kingdom AlphaDEX Fund shares are currently trading down about 0.6% on the day.