The iShares Core S&P Mid-Cap ETF (NYSEArca: IJH), one of the largest domestic mid-cap ETFs, also has a five-year correlation to DNLDX of 0.92, according to Raltin data. IJH tracks the widely followed S&P MidCap 400 Index and charges just 0.07% per year.

Advisors looking for alternatively-weighted mid-cap ETFs that can be suitable replacements to actively managed funds have plenty of alternatives as well. The First Trust Mid Cap Core AlphaDEX Fund (NYSEArca: FNX) has a five-year correlation to DNLDX of 0.90, according to Raltin data.

FNX pulls its holding from the S&P MidCap 400, but picks those names based on growth factors, sales to price and one year sales growth, along with value factors like book value to price, cash flow to price and return on assets. The fund charges 0.62% per year, which is pricey compared to cap-weighted mid-cap ETFs, but still a favorable price point compared to many active mid-cap funds.

For more information on middle capitalization stocks, visit our mid-cap category.