Looking at individual sectors, transport and logistics, business services and information, and media and technology were the most confident. The least confident included manufacturing, wholesale trade and mining - with mining reporting a significant drop.
Commonwealth Bank's executive general manager of corporate financial services, Symon Brewis-Weston, said that despite the confident reading, most firms were approaching 2013 with caution.
"We're finding that it's something of a wait-and-see period for the mid-market," he said.
"Companies are placing less emphasis on growth at the moment and ensuring they have the financial support required for any unforeseen challenges in the future."
The index showed moderate optimism among the states and territories, with Victoria and Tasmania recording steady confidence, both rising to 14 from 6.2.
Meanwhile, New South Wales and Australian Capital Territory were the only regions in decline, both falling to six from 10.4.
-AAP
