The final quarter of 2015 was an inflection point for businesses and the economy, as the long bull market ground to a halt, valuations of highly prized companies took a nosedive, and venture capitalists began shutting the taps for hefty rounds of financing.

One area that especially felt ripple effects from the downdraft was the middle market, comprising companies with annual revenues between $10 million and $1 billion. The segment is important because such companies are big drivers of job growth, employing 48 million workers, roughly one-third of the total U.S. workforce.

That's according to the fourth quarter survey by the National Center for the Middle Market (NCMM), a business advocacy group that operates in conjunction with Ohio State University. NCMM compiled its data, released Wednesday, by polling 1,000 C-suite executives in December of 2015.

The survey found that confidence among those executives is on the wane: 47 percent said they were confident about the global economy, a decrease of two percentage points from the third quarter, and a decrease of five percentage points from the fourth quarter of 2014. Confidence in the U.S. economy was at 67 percent, a decline of five percentage points compared with the third quarter of 2015, and a drop of six percentage points compared with the fourth quarter of 2014.

Nearly 70 percent of companies said they experienced positive revenue growth in the final quarter, but the rate of growth appears to be slowing. In the past 12 months on average, mid-market companies reported revenue growth of 6.1 percent, more than one percentage point lower than both the third quarter of 2015 and the fourth quarter of 2014. Looking at the next 12 months, these companies said they expect revenue growth of 3.7 percent in the fourth quarter, also a lower percentage than both Q3 2015 and Q4 2014.

Meanwhile the decreased revenue growth and shrinking prospects for growth in the next 12 months took their toll on hiring plans. In the fourth quarter, 39 percent of firms reported adding more workers, a three percentage point decrease compared with the previous quarter.

In real terms, middle market companies increased their head counts by 3.6 percent in the fourth quarter of 2015, a decrease of 1.4 percentage points from the fourth quarter of 2014. Looking forward to the year ahead, these firms said they planned to increase workers by 2.7 percent, a decrease of 1.3 percentage points compared with the fourth quarter of 2014.

"Middle market businesses are tempering hiring expectations because of declining confidence about economic conditions, particularly the global economy," said Thomas A. Stewart, executive director of NCMM in a press release.

Like their smaller peers, mid-market firms list staffing challenges, the business growth environment, and increasing costs as their biggest challenges for 2016.