The mood of the nation's small-business owners continued to fade last month, as weaker earnings and spending plans kept economic optimism at record lows, the National Federation of Independent Business  reported this week.

Fewer owners in July were planning to boost capital spending in the months ahead, while earnings and inventory levels declined, the Washington-based lobby group said. 

Overall, the group's monthly small-business optimism index fell for the third straight month, dropping by one point to 88.2 and marking the longest stretch of recession-level readings since the index was launched over 25 years ago.

Meanwhile, the number of owners reporting higher selling prices rose again last month, with a majority citing inflation  as a top business concern.

"The inflation problem is getting worse, not better," William Dunkelberg, the group's chief economist, said in a statement.

The index is based on survey responses from more than 1,800 small-business owners nationwide.