Confidence among small-business owners fell last month to the lowest level since July, according to NFIB's optimism index. The index dropped to 86.8 from 88 in February. Low sales are still business owners' biggest concern, and credit remains tight. "Something isn't sitting well with small-business owners. Poor sales and uncertainty continue to overwhelm any other good news about the economy," said NFIB Chief Economist Bill Dunkelberg.