The Federal Reserve will probably reduce its bond-buying program in December rather than in September as current Treasury yield levels indicate, according to Morgan Stanley’s Matthew Hornbach.

“December is a more likely time for tapering to begin,” according to a June 7 note written by Hornbach, the head of U.S. interest-rate strategy at the bank, one of the 21 primary dealers that trade directly with the Fed.

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An increase in Treasury yields to 2.25 percent from 2.17 percent today would be an opportunity to increase portfolio duration, New York-based Hornbach wrote. Such a yield would represent forecasts for a reduction in July or sooner, which would be unlikely, the report said. Duration is a measure of a bond’s sensitivity to changes in yield, and a longer duration indicates a more bullish position.

The benchmark 10-year yield was little changed as of 12:38 p.m. in Tokyo, according to Bloomberg Bond Trader prices. The price of the 1.75 percent security due in May 2023 was 96 9/32.

Treasurys have fallen for six weeks, the longest streak in four years. U.S. payrolls advanced while the jobless rate rose in May, the Labor Department reported on June 7, supporting speculation the Fed will reduce its monetary stimulus.

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 last week.