The New York-based Conference Board's forecast of future economic activity fell by 0.1%, matching the consensus estimate of Wall Street economists. The group revised May's number down to a 0.2% decrease from a 0.1% increase.
The report indicated that the economy may not improve over the next six months.
"The report is saying there's no pickup, there's no recovery from where we are six months ahead," said Allen Sinai, chief economist at Decision Economics.
He said the report showed a fragmented economy, with housing and finance in "a depression" alongside healthy sectors like health care and exports.
The situation is complicated by the fact that while real GDP has not declined, many important monthly indicators - such as job creation - have shown weakness.
"So, how do I characterize it? More of the economy is doing poorly than well, so I'm calling it a mild recession," Sinai said.
The leading indicators index is an aggregate of data such as stock prices, unemployment claims, weekly manufacturing hours and the difference between short-term and long-term interest rates.
Four of the 10 key factors contributed positively to the index. Most important were building permits, an increase of 0.3%, and interest rate spread, an increase of 0.2%.
Of the six factors that weighed down the index, money supply fell by 0.3% and stock prices decreased by 0.2%.
