The Federal Reserve realizes, at some point, it has to scale back its $85 billion-a-month bond purchases, and the acknowledgement of this eventuality has made the stock market "very unpredictable," Jurrien Timmer, portfolio manager and director of global macro at Fidelity Investments, told CNBC on Thursday.
Since Fed Chairman Ben Bernanke's testimony and the Fed minutes last week, investors have been waking up to the prospect of the central bank slowing its quantitative easing sooner than expected—a phenomenon that Timmer called the "Taper Tantrum."
The term "taper" has recently become common parlance in the investment community, after hedge fund titan David Tepper appeared on "Squawk Box" on May 14. The founder and president of Appaloosa Management said the Fed has to taper to keep the stock market advance on an even keel.
(Read More: It's a 'My Cousin Vinny' Market, Bullish Tepper Says)
"The Fed knows it eventually is going to have to taper," Timmer said on "Squawk Box" Thursday.
He also referred to that recent Tepper appearance and the hedge fund manager's 2010 "Squawk" interview that sparked the so-called Tepper Rally.
"It was the 'Tepper Rally'—now it's the 'Taper Tantrum,'" Timmer quipped.
"The bond vigilantes have finally come out of the woodwork," he said, warning that if the yield on the 10-year Treasury continues to go higher to the 2.5 percent level, "it's going to start to undermine the equity market" at some point.
But stocks have avoided the spring swoon of the previous three years because, Timmer added, "the Fed is not only printing, but printing by the bucket-load. And the Bank of Japan is undergoing this incredible monetary experiment of doubling the monetary base."
While stocks have held up, there's been a bit of a stealth correction, he contended, pointing to the "relative performance of energy stocks, for instance, to find the weakness."
Timmer said he's still using about 60 percent stocks and 40 percent bonds as a benchmark asset allocation with some other positions thrown in too, like gold.
He said he bought the precious metal when it dipped to around $1,300 an ounce. "That seems like a pretty natural floor." He continued, "Based on some of my analysis, gold could be at $2,000 or should be at $2,000."
"That's a pretty good risk-reward," Timmer said.