Smaller, privately held companies are seeing a significant slowdown in their rate of sales growth, according to data from research firm Sageworks.

After two years of strong sales growth at around 7%, small U.S. companies are experiencing the slowest rate of sales growth since the recession, according to Sageworks in Raleigh, N.C.

That growth rate is at less than 1% so far this year. Sageworks noted that 2013's numbers are year-to-date estimates and are subject to revision.

The firm also discovered that sales growth for businesses with less than $5 million in annual sales is virtually non-existent so far in 2013.

While profit margins are healthy for now, they may be difficult to sustain if sales growth does not increase, according to Sageworks.

“This slowdown in the rate of sales growth does not bode well for small business hiring,” the firm said. “Small businesses were reluctant to hire when they were growing sales at a rate of 7%.”

Meanwhile, smaller manufacturing, wholesale and retail companies are seeing a sales contraction in 2013 to date, Sageworks said.

The firm said it possesses a proprietary database of privately held company financial statements aggregated by industry. Each day, approximately 1,000 of these financial statements are collected by Sageworks from accounting firms, banks, and credit unions through a cooperative data model with the firm's clients, Sageworks said.