Higher rates? I don't care, as long as Yellen keeps her word: Portfolio manager

September hike a reality?

If Federal Reserve policymakers, including Chair Janet Yellen, are taken at their word about any interest rate hikes being gradual, exactly when the central bank moves should not matter to stock investors, said Margaret Vitrano, portfolio manager at ClearBridge Investments.

"We all know rates are gradually moving higher. As an equity investor, I don't know that I really care. Rates can still move higher and the market can march higher as long as the slope of the curve isn't too steep," Vitrano told CNBC's "Squawk Box."

The Fed speak from Yellen and others at last week's Jackson Hole Economic Symposium in Wyoming seemed to be screaming that loud and clear.

"I think they're showing us that the slope of the curve is not going to be that steep," said Vitrano, who co-manages ClearBridge's Large Cap Growth and All Cap Growth funds.

The central bank's reluctance to hike rates for the second time in more than a decade shows its "erring on the side of caution," she said, predicting a December move. "I don't know why they need to hurry."

Mike Ryan, chief investment strategist for UBS Wealth Management Americas, agrees with Vitrano in predicting that a December rate increase by the Fed is "most likely."

During the same interview on "Squawk Box," Ryan said, "I think [Yellen] confirmed it's coming this year." But he inserted a caveat on the timing. "I won't rule out September, if we do get a flurry of strong data."

Ryan said Friday's release of the government's August employment report could be a major factor in the Fed's decision.

But in general, he argued: "The U.S. economy is in relatively solid shape. It's not robust growth. It's not the kind of growth we've seen prior to the [2008 financial] crisis. But the economy is actually doing OK."

"I think what the Fed is concerned about is what's happening in the rest of the world," he added.

Ryan said he chalks up the Fed's will-they-won't-they monetary policy to the difficulty of raising rates at a time when many global central banks are easing in an attempt to eke out any growth from their economies.

The Fed raised rates for the first time since 2006 in December 2015.