If the U.K. votes to leave, "it could be very negative, but the epicenter would be the U.K., maybe some spillover to Europe and little to the U.S. We don't think this is going to be a major factor for the global economy and the U.S. economy," Sinche said.
The vote comes at a time when markets were already testy, with global bond yields falling to record lows and some, such as the 10-year German bund, falling into negative territory. The 10-year Treasury yield fell as low as 1.47 percent, its lowest since 2012. The 10-year was yielding about 1.60 percent late Friday.
Stocks were lower on the week, with the S&P 500 down 1.2 percent at 2,071.
"It's going to take a long time for a separation to be felt," said Christopher. "On a strong negative vote, you could test [S&P 500] 2,000 or a little bit below, at support levels. We think it's going to be a buying opportunity."
Christopher said the 10-year yield could test its all-time closing low around 1.39 percent. "You could hit that again," he said. "We think investors should stay in the middle of the curve and look for high-quality corporates."
"The interesting thing is we could see the currencies against the dollar moving in different directions, maybe offsetting each other. You could see the pound at 1.30, 1.25 even. You could see the euro weaken but not as much as sterling," said Christopher. The pound was trading at about 1.43 against the dollar Friday.