MDY

SPDR S&P Midcap 400 ETF Trust

An exchange-traded fund that tracks the S&P MidCap 400 index, a basket of about 400 mid-sized U.S. companies, letting everyday investors buy a slice of all of them in one trade. It was launched in 1995 by State Street Global Advisors, among the earliest ETFs ever created. Its SPDR name is short for Standard & Poor's Depositary Receipts — and because the acronym spells "SPDR," traders nicknamed these funds "spiders."

Exchange-traded fund tracking mid-cap US equities