The WisdomTree U.S. MidCap Dividend ETF (DON) made its debut on 06/16/2006, and is a smart beta exchange traded fund that provides broad exposure to the Style Box - Mid Cap Value category of the market.What Are Smart Beta ETFs?The ETF industry has long been dominated by products based on market cap weighted indexes, a strategy created to reflect the market or a particular market segment.Investors who believe in market efficiency should consider market cap indexes, as they replicate market returns in a low-c ...