WILLIAMSTOWN, MASS. ( TheStreet) -- Nontraditional ETF strategies have created a rift in the family of ETF funds. First introduced as passive, low-cost and transparent vehicles, ETFs now utilize a host of indexing approaches. While funds like Direxion Daily Financial Bull 3X ( FAS), U.S. Natural Gas ( UNG) and iPath India ( INP) have drawn a considerable amount of investor attention, they are cloaked in complexity and best left to experienced investors.The unique structure of ETFs has allowed the funds to take on exotic new incarnations. From ultra ETFs to funds of funds, the ETF industry is diving into every niche to capture market share. This new generation of ETFs strategies layer risk onto the old ETF model. Four types of nontraditional ETFs that should be understood fully before utilized are leveraged ETFs; futures-based commodity ETFs; ETNs; and ETFs of ETFs.