"Global populism is the wave of the future, but it has taken a wrong turn in America," he wrote.
"Investors must drive with caution, understanding that higher deficits resulting from lower taxes raise interest rates and inflation, which in turn have the potential to produce lower earnings and P/E (price-earnings) ratios," Gross added.
Gross' fund through Monday returned 4.5 percent this year, outpacing 68 percent of its peers, according to Morningstar Inc data. Janus last month announced a plan to merge with London-based Henderson Group Plc.
This article was provided by Reuters.