A measure of future U.S. economic growth increased in the latest week, while the annualized growth rate fell to an 18-week low, 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 121.5 in the week ended June 22 from 121.2 the previous  week. That was originally reported as 121.3.

The index's annualized growth rate fell to minus 3.6 percent, its lowest level since mid-February 2012, from minus 3.5 percent a week earlier.