But Matthew Shay, the group's president and CEO, said the calculations were made before the shutdown.
"What we are trying to balance here is the underlying fundamentals with the economy, which seem strong, against all that consumer unease and the uncertainty coming from Washington," Shay said in an interview with The Associated Press.
The Labor Department reported Thursday that the number of Americans seeking unemployment benefits rose by only 1,000 last week.
However, the less volatile four-week average for applications fell to 305,000. That's the lowest since May 2007, seven months before the recession began.
Later Thursday, the Institute for Supply Management reports on growth at U.S. services firms in September. Economists believe that the index declined to 57.5 in September, according to a survey by FactSet.
That would be down from an eight-year high of 58.6 in August. Any reading above 50 indicates growth. The ISM is a trade group of purchasing managers.