GYLD reaches across asset class boundaries in its search for yield. The fund allocates equally across five main categories of global securities: equities, sovereign debt, corporate debt, real estate and alternatives. (Real estate and alternatives here mean primarily REITs and MLPs.) The fund takes on risk as it searches for income risk that's hard to measure but that's palpable in its holdings list. Currency risk (and reward) is in play here too as often more than 1/2 of the exposure is outside the US, according to the issuer. Still, the fund's structural diversity tamps down its risk. The Underlying Index is rebalanced and reconstituted quarterly.