Policy makers led by Chairman Ben S. Bernanke will trim their so-called quantitative easing program to $65 billion a month at the Oct. 29-30 meeting of the Federal Open Market Committee, from the current level of $85 billion, according to the median estimate in the survey of 59 economists this week. In a similar survey before the Fed’s April 30-May 1 meeting, economists predicted the first move in the fourth quarter.

Debate among central bank policy makers over when and how to dial back their unprecedented easing campaign has shaken financial markets. The Standard & Poor’s 500 Index has dropped 2.8 percent since reaching a record closing high on May 21, and the yield on 10-year Treasurys has risen to 2.08 percent from as low as 1.63 percent last month as investors weighed the timing of a reduction in the central bank’s stimulus.

“Even those who are advocating for tapering are thinking that it could be a pretty small first step to see how it goes,” said Julia Coronado, chief economist for North America at BNP Paribas in New York and a former Fed economist. “That’s one of the few things we’ve learned” from the debate among policy makers.

When the first move comes, officials will split their $65 billion in purchases between $30 billion a month of mortgage bonds and $35 billion a month of Treasurys, a $10 billion reduction in each category, according to the survey, conducted June 4-5.

Prior Survey

In the previous survey, economists expected the tapering to be larger, with the Fed cutting purchases to $50 billion from $85 billion in its first step down.

Two of the 59 economists surveyed this week expect the pace of purchases to be reduced at the FOMC meetings on June 18-19 or July 30-31. Sixteen say tapering will begin at the Sept. 17-18 meeting, 14 see it happening Oct. 29-30 and 15 forecast the first tapering Dec. 17-18. Twelve see tapering next year or later.

“If jobs growth continues in the 150,000-to-200,000 per month range, that’s probably sufficient to lower the unemployment rate slightly,” said Tom Lam, chief economist at DMG & Partners Securities in Singapore. “Coupled with real GDP growth recovering to 2.5 percent, that would be sufficient for them to consider tapering modestly at the December meeting.”

Stocks, Bonds

The Stoxx Europe 600 Index was little changed at 291.80 at 9:55 a.m. in London. The MSCI Asia Pacific Index lost 0.3 percent to 130.90. The yield on the 10-year German bund fell 2.3 basis points to 1.496 percent.

Philadelphia Fed President Charles Plosser has called for tapering to start as early as the central bank’s next meeting. Federal Reserve Bank of New York President William C. Dudley said in an interview with Bloomberg News last month that he would like to wait three or four months to see “how the tug-of- war between the fiscal drag and the improving economy are going to sort of work their way out.”

St. Louis Fed President James Bullard said May 23 in London that more disinflation could prompt additional asset purchases by the central bank, and Boston’s Eric Rosengren said the Fed should increase purchases if the incoming data “do not reflect improvements” in unemployment and inflation.

Jobs Report

Policy makers will have a clearer view of the employment picture after Friday’s 8:30 a.m. monthly jobs report from the Labor Department. Economists in a separate Bloomberg survey expect the report to show that employers added 163,000 jobs in May.

That would be little changed from the 165,000 that were added in April. Over the course of the last year, payroll growth has averaged 173,000 a month.

Investors worried about the central bank winding down stimulus may be missing the underlying improvement in the economy, James Paulsen, the chief investment strategist at Wells Capital Management in Minneapolis, said in an interview on Bloomberg Television.

“When the Fed does start to end QE, it will actually build confidence because it is another sign that the economy is getting better,” Paulsen said.