Gross on Tuesday described the German 10-year bund the "short of a lifetime" , comparing it to George Soros' famous short on sterling in 1990s. But Pimco portfolio manager Mike Amey told CNBC Wednesday that, while he respected Gross, "not everyone gets every call right."
The surge in the price of a 10-year German bund and its tumbling yields - which have been approaching negative territory -- means it is just a matter of time before it moves in the opposite direction, Gross said.
"It's just a question of when," Gross, who now runs the $1.5 billion Janus Global Unconstrained Bond Fund, told CNBC. "It's certainly a trade that doesn't cost you anything in the short term, because it doesn't yield anything and it has the ultimate potential of a 10 or 15 percent (return) over a one- or two-year period of time."
But Amey argued that technicals - not fundamentals -- were driving the bond market. This indicates that he thinks patterns in market activity are behind the moves, rather than macroeconomic factors (which can be misread by markets, but tend to lead prices to their "correct" level).
"Bill made a lot of money for a lot of people over a long period of time, and not everyone gets every call right. I respect what Bill says and always have done. Our view at the moment is that the technicals will dominate the fundamentals," Amey told CNBC.
"Nobody is arguing that 10 basis point move on a 10-year bund is good value - but unfortunately, at the moment, the fundamentals are not what is driving the bund market."
Bunds were yielding 0.127 percent on Wednesday after hitting a record low of 0.049 per cent in intraday trading last week, as the European Central Bank's 60-billion-euro-a-month bond-buying stimulus program gets underway.
Earlier this week, Pimco's Head of Portfolio Management in Germany, Andrew Bosomworth said he expected to see sharp moves in Germany's 30-year bund, with the yield sinking to zero from current yields of around 0.5 percent.
"Where the highest-yielding assets are, in a world in which there is no supply, then that is the one that can move the most," Amey said