...NEW YORK (S&P Global Ratings) Oct. 18, 2018--S&P Global Ratings today said it lowered its fund credit quality rating (FCQR) on the iShares Broad USD High Yield Corporate Bond ETF (USHY), managed by BlackRock Fund Advisors (BFA), to 'Bf' from 'B+f'. At the same time, we affirmed our '##' fund volatility rating (FVR). The 'Bf' FCQR signifies that the credit quality of the fund's portfolio exposure is very weak. Initially, we assigned our 'B+f' rating on the fund, based in part on an assessment of the credit quality of the fund's benchmark index portfolio, ICE BofAML US High Yield Constrained Index, prior to the fund's official launch. We assessed the fund's index portfolio to determine the preliminary FCQR, given the fund's investment objective to track the investment results of the benchmark index through a passive investing approach. We are now lowering the FCQR because since the fund launched, its underlying portfolio of investments has exhibited portfolio credit that has steadily and...