 The funds are formulated as unit investment trusts.In 2007, SSGA rebranded its other United States ETFs as SPDRs, including the StreetTRACKS family and its other flagship ETF shares, the DOW DIAMONDS, that tracks the Dow Jones Industrial Average.This move united all U.S. ETFs managed by SSGA, a total of 23 at that time, under a single brand.