FNX attempts to improve upon the results NASDAQ US 600 Mid Cap index (the parent index) by rescreening each security twice, by both growth and value characteristics assigning whatever score is highest as the stock's style score. The underlying index selects 450 stocks by factors such as recent price appreciation, price/sales, sales growth, price/book value, price/cash flow and return on assets. The stocks are ranked, and then tiered equal-weighting is applied to the top 75% of securities. Its weighting scheme leads to a perpetual small-cap tilt, which along with sector biases, raises the fund's market risk. The index is reconstituted and rebalanced quarterly. Prior to April 8, 2016 the fund tracked the Defined index, which had a slightly different universe but had the same factors and methodology.