This will cause a 'substantial pullback': Blitzer

Fed watchers must shift gears: S&P 500 Chairman

The frequency is more important than the timing of interest rate hikes by the U.S. Federal Reserve, according to the managing director of S&P Dow Jones Indices, who believes that global sentiment would be dented if the central bank acts too quickly.

David Blitzer has the overall responsibility for index security selection at the research firm, which manages the and the Dow Jones Industrial Average.

He told CNBC Tuesday that the initial move by the Fed would happen in the last quarter of 2015 - at the earliest.

"The pace has to be slow and the real question is not the timing of the first one...but the timing of the second one," he said.

"If they come pretty close together - let's say two consecutive meetings - a lot of people are going to say: 'Oh, they're really worried about inflation, all bets are off,' and there will be a substantial pullback."

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If the Fed members skipped at least one meeting before a second rate rise then market participants would likely be more relaxed and curb any sell-off in equities, Blitzer added.

Global benchmarks, led by the S&P 500, have been on what seems like a never-ending bull run since 2009, with many economists crediting the aggressive monetary policy put in place by the Fed for the push higher. Its main benchmark rate - which prices all sorts of loans and mortgages in the U.S. - has been at record lows and it finished its third bond-buying program last year.

Major U.S. indexes have hit record highs, but have stalled this year, with bond guru Bill Gross warning this week that the roaring market would run out of steam "with a whimper." This comes as the Fed looks likely to start to raise rates this year, with market participants divided over when the first move might come.

Blitzer added that Fed members have changed their tone in recent meetings and have gone back to concentrating on economic data, rather than trying to detail a roadmap for investors.

Charles Evans, the president of the Federal Reserve Bank of Chicago, said at an event in Indiana on Monday that hiking rates did not seem appropriate until next year in the wake of weak first-quarter economic data. The U.S. economy expanded by an annual rate of just 0.2 percent over the period, figures published last week revealed.

These first-quarter struggles for the U.S. economy make monetary policy tightening more feasible sometime in early 2016, Evans said.