We're not done with volatility: Jason Trennert

Expect more volatility ahead: Pro
Market bottom's in and we're buying: Pro
Following Fed's timeline: Economist
Market quick correction reminiscent of 1997: Expert

The market selloff hasn't run its course, even with two-straight trading sessions ending sharply higher, strategist Jason Trennert warned on Friday.

"The volatility is not over for two reasons. One, we don't know what the Fed's going to do. Two, I think the China devaluation was a game changer," the chief investment strategist at Strategas Research Partners told CNBC's "Squawk Box."

Trader on the floor of the New York Stock Exchange.
Lucas Jackson | Reuters

Many investors across the globe were bracing for a possible September rate hike by the U.S. central bank. Nevertheless, that outlook has become more uncertain as different Fed officials have given conflicting views.

On Wednesday, New York Fed President William Dudley expressed a dovish view that the argument for a September increase is less compelling amid the markets' recent swings. But Kansas City Fed President Esther George said she wasn't so sure the selloff changed the need for a rate hike.

Wells Fargo Investment Institute's Darrell Cronk told "Squawk Box" he wants the central bank to hike interest rates so the markets can move on.

"I don't think the markets would embrace that," he said. "We think the Fed has the ammunition. We saw positive durable goods data and higher GDP data; it's all there for them to raise rates."

The flags of the U.S. and China.
China dumping Treasurys? Here's what you must know
China cenbank injects 60 bln yuan via short-term liquidity operations

Trennert said the Chinese government's decision to devalue its currency, the yuan, shows a lack of competence by China's leadership.

"They say there are two types of economists. Those who don't know and those who don't know they don't know. I think we've realized [the latter] with China," he said. "Until those two things are resolved, I think it's going to be hard for the market to make a big bounce from here."

In another "Squawk Box" interview, Fidelity Investments' Jurrien Timmer said investors overreacted to China's move.

"People quickly extrapolated the worst-case scenario of the China devaluation and you combine that with an August market when a lot of people aren't at their desk … and you get these crazy moves," Timmer said.