A measure of future U.S. economic growth held steady at its highest level in more than three years while the annualized growth rate hit a four-week high, a research group said on Friday.

The Economic Cycle Research Institute, a New York-based independent forecasting group, said its Weekly Leading Index stood at 132.4 in the week ended September 13, matching a revised 132.4 the prior week. The previous week's result was originally reported as 132.3.

The index's annualized growth rate rose to 4.5 percent, the highest since the week ending August 16. The prior week's rate was revised up to 4.3 percent from 4.1 percent.