The National Federation of Independent Business (NFIB) released its small-business optimism index for the U.S. on Tuesday. The index rose to 93.6 in April from 92.6 in March.

5 of 10 sub-indexes increased last month, 1 sub-index fell, while 4 were unchanged.

"The Federal Reserve continues to send out a message of economic weakness, indicating that the economy is too weak to be able to handle a 25 basis point increase in the Federal Funds rate. This reinforces the uncertainty felt on Main Street and supports the reluctance to spend and hire reflected in the NFIB measures," NFIB Chief Economist Bill Dunkelberg said.