The Federal Reserve has lost credibility by failing to deliver a clear message during its interest rate policy announcement last week and because Chair Janet Yellen contradicted its decision in her speech, RBC Capital Market's Jonathan Golub said Friday.
"They took an unsettled situation and they just threw kerosene on that fire through all of their statements," RBC's chief U.S. market strategist told CNBC's "Squawk Box." "They didn't fix this with one speech.
During her speech Thursday at the University of Massachusetts at Amherst, Yellen said it would be appropriate to raise the Fed's benchmark fed funds rate "sometime later this year." However, she noted that the decision to normalize interest rates—which the Fed has held near zero since December 2008—would remain dependent on economic data.
Last week, the Fed's policymaking committee voted to leave the fed funds rate unchanged. Afterward, Yellen cited the need for further evidence of labor market improvement and signs inflation is moving toward the Fed's target, as well as concerns about economic weakness overseas.
DRW Trading Group strategist Lou Brien said Friday the manner in which the Fed announced its decision was confusing. He said Yellen suggested the Fed may still raise interest rates this year, but presented inflation as a longer-term project and singled out trouble in emerging markets, which would probably take a long time to settle.
"What are they talking about? They're not raising because of these concerns, which are real concerns, and yet they could do it in October?" he said in a "Squawk Box" interview.
Yellen's speech on Thursday gave market watchers certainty that they could put the Fed's "mixed message" from last week behind them, he added.
U.S. stock market futures moved sharply higher ahead of the opening bell on Friday, with traders citing the clarity offered by Yellen's comments in Amherst.
Read More Yellen nudges markets slightly on rates
Golub said the market does not want to see interest rates soar to 2.5 percent within six months, but investors generally support normalization. History shows that rate hikes do not have to be disruptive to markets, he added.
"It's very clear on days where interest rates rise, stocks go higher. It happens across all sectors, and it happens across virtually all markets," he said.
With U.S. Treasurys providing meager returns in recent years, investors have fled to stocks and other higher-yielding assets.
—CNBC's Jacob Pramuk contributed to this story.