Investors worry that the eight-year bull market might come to an end due to higher interest rates, BofA Merrill Lynch Fund Manager Survey said in a report.Ten-year treasury yields of 3.5% to 4% are needed to trigger equity bear market. Investors believe that higher interest rate is a stronger catalyst than weaker earnings and Protectionism. “Investors identify higher interest rates rather than weaker earnings as the catalyst most likely to end the 8-year bull market in equities,” the report said.Fund managers cite European elections raising disintegration risk as the biggest tail risk, closely followed by a trade war and a crash in global bond markets.