State Street SPDR S&P 400 Mid Cap Growth ETF(AMEX:MDYG)

MDYG curates a portfolio of S&P MidCap 400 (commonly known as S&P 400) companies with high sales growth, high valuations and momentum. It starts selecting constituents further down the market-cap spectrum, leading to a lower than usual average market-cap and even some exposure to small-caps. Unlike some of its peers, MDYG isn't a pure growth fundits methodology allows securities to be classified into multiple categories. As such, its holdings could overlap with so-called core funds or even value funds. The fund may also heavily overweight financials, while underweighting other sectors such as consumer cyclicals. Additionally, instead of replicating the index, MDYG uses sampling indexing. The index is weighted by float-adjusted market-cap and rebalanced on a quarterly basis.