A measure of future U.S. economic growth picked up last week, rising to its highest level in four months, a research group said on Friday.

The Economic Cycle Research Institute, a New York-based  independent forecasting group, said its Weekly Leading Index  rose to 124.9 in the week ended Sept 7 from an upwardly revised 124.1 the previous week. That was originally reported as 123.7.

The index's annualized growth rate also rose, to its highest level since August 2011, at 2.1 percent from 1.4 percent a week earlier.