First Trust Mid Cap Core AlphaDEX ETF (FNX) Shows Diversification but Faces Yearly Decline The First Trust Mid Cap Core AlphaDEX ETF, with over $1 billion in assets, offers broad exposure to mid-cap stocks, heavily weighted in financials. Despite its diversification, FNX is down over 12% year-to-date and 3% over the past year, reflecting broader mid-cap market challenges in 2025.2