Fear and uncertainty are driving smaller private equity deals — one of the last robust M&A markets in the present economy — industry insiders say.

After years of looking to sell to capitalize on a healthy economy and outsized performance, business owners are now being driven to sell by future economic uncertainty and the worry that a changing tax code could further crimp the profit they make in a sale.

"A lot of company owners that are looking for a deal are being driven by fear," said Stuart Johnson, Powell Goldstein LLP corporate finance attorney. "They're scared about where the economy is going and they're looking for a financial partner so they can sleep at night."

The second concern is the looming presidential election. Some business owners fear a change in the White House means an increase in capital gains taxes.

"Others aren't scared," Johnson said. "But they're looking ahead."