Small business optimism sunk lower than expected in June, the National Federation of Independent Businesses announced today.

The NFIB's Small Business Optimism Index dropped 3 points since May, marking the biggest drop since October 2011. The news comes as somewhat of a surprise, as economists predicted a less dramatic fall earlier this month, according to The Wall Street Journal.

"All in all, this month's survey was a real economic downer," NFIB Chief Economist William Dunkelberg said in a statement to the press.

What's weighing on the minds of America's small business owners?

According to the report, nearly 23% of owners say weak sales is the biggest problem, while 21% say taxes and 19% cite unreasonable regulations and red tape.

This news comes hot on the heels of a similarly dreary announcement by the Institute for Supply Management, which said that America's manufacturing sector shrank in June for the first time in three years.