A measure of future U.S. economic growth improved last week, but the annualized growth rate remained in negative territory after a downward revision to the previous week, 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 125.4 in the week ended May 4 from 124.6 the previous week. That was originally reported as 124.7.

The index's annualized growth rate held steady at minus 0.1 percent for the second week in a row.