This year has proven to be an average one for major asset classes — in multi-asset portfolios, neither equities or bonds performed particularly well. Next year could be more of the same for mostly everything but U.S. dollars and short-term money markets, according to analysis from Goldman Sachs.

"We generally expect another year of low risk-adjusted returns across assets in 2019," Goldman Sachs global equity strategist Christian Mueller-Glissmann said in a note to clients Tuesday. "We prefer cash and remain [overweight]."

Goldman said it is "modestly pro-risk" in its asset allocation: The firm is overweight equities and commodities and underweight bonds. Mueller-Glissmann said he still expects low returns for bonds and predicted their value as a hedge in a "risk off" trade is "likely to remain poor."