The head of US equity derivatives strategy at UBS said she expected the S & P 500 to fall at least 10 per cent from its peak within a month. "I am tactically bearish on the next two months," Rebecca Cheong wrote in a note to clients on Tuesday. "The slightest bit of disappointment in the upcoming economic data could trigger a major pullback." She advised investors to buy tail hedges in ETFs to protect against losses and named the iShares Russell 2000 ETF (IWM), the Financial Select Sector SPDR Fund (XLF US) and the iShares iBoxx High Yield Corporate Bond ETF (HYG) as top choices.