“The S&P Mid Cap 400 Index trailing P/E of 20.8 is just a 4% premium to its median level since 2001, while the S&P Small Cap 600 Index current P/E of 24.6 is 14% above its median,” said S&P Capital IQ.

Although mid-caps are often overlooked by investors, it cannot be ignored that mid-caps have a lengthy history of out-performance over large-caps. Since the March 2009 market bottom, IJH has outperformed the S&P 500 by almost 5,900 basis points. [Mid-Cap ETFs Soar]

Companies in the S&P MidCap 400 Index are growing faster and carry less debt than large-cap S&P 500 stocks. Moreover, mid-caps have greater access to capital markets than small-caps.

IJH, which charges 0.15% per year, brought in over $2.1 billion in new assets during the second quarter, ranking the fund fourth among all ETFs for second-quarter inflows.

iShares Core S&P Mid-Cap ETF