The core inflation index, which excludes volatile components such as food and energy prices, rose 6.5% year over year, marking the hottest reading since August 1982 (per a CNBC article). Below, we have presented five popular mid-cap ETFs: Vanguard Mid-Cap ETF VO Vanguard Mid-Cap ETF seeks to track the performance of the CRSP US Mid Cap Index, which measures the investment return of mid-capitalization stocks. VO has AUM of $54.93 billion.