Stocks fell again on Tuesday.
The S&P 500 fell 0.2 percent for its fourth consecutive decline. It is now 2.6 percent below its record high.
However, it was the STOXX Europe 600 that has been hit particularly hard on concerns over a possible UK exit from the European Union. It tumbled 1.9 percent on Tuesday and fell 7.4 percent over the past five trading sessions.
Bond yields also fell again on Tuesday. The US 10-year Treasury yield fell to 1.611 percent, the lowest since December 2012, from 1.616 percent on Monday. The 10-year German bund yield fell below zero for the first time ever.
Brian Belski, chief investment strategist at BMO Capital Markets, thinks there will be more near-term volatility. "This summer, heading into the election, it's going to be bumpy," he told CNBC.
In contrast, Ivan Kollar, a portfolio manager at Marketocracy, said in an interview that stocks "are about to embark on the next upswing... which will bring the market to 2400 and beyond".