SPDR® funds are shares of a family of exchange-traded funds (ETFs) traded in the United States and managed by State Street Global Advisors (SSgA). Informally, they're also known as Spyders or Spiders. SPDR®'s a trademark of the McGraw-Hill Companies, Inc. The name's an acronym for the first member of the family, the Standard & Poor's Depositary Receipts, the biggest ETF in the U.S., which's designed to track the S&P 500 stock market index. The funds are formulated as Unit Investment Tru… (More on Spdr)