Stock markets on the Chinese mainland capped off a roller coaster session Wednesday with modest gains as investors hunkered down in the absence of any obvious trading cues.

The key Shanghai Composite Index gained 5.77 points, or 0.25 percent, to close 2,320.91; while the Shenzhen Component Index finished at 9,548.13 after rising 11.95 points, or 0.13 percent.

Combined trading volume at the two exchanges totaled 188.8 billion yuan ($30.36 billion), down sharply from Tuesday's 240.5 billion yuan.

Both indices opened lower Wednesday as several heavily weighted sectors, including banking and property development, pressed into negative territory. The afternoon session saw the markets recover as aircraft manufacturing, shipbuilding and environmental protection stocks climbed higher, lifting both markets north of even by the close of trading.

Aviation shares ended up leading the market in terms of gains Wednesday. China AVIC Avionics Equipment Co jumped 10.01 percent to 20.55 yuan.

China Vanke Co carried its rally into a third consecutive trading day, gaining 6.87 percent to 16.170 yuan.

Shipbuilders also notched respectable gains following reports Wednesday that China plans to build its first aircraft carrier on Shanghai's Changxing Island. Southern China's biggest shipbuilder, Shanghai-based China CSSC Holdings Ltd, tacked on 2.27 percent to 23.41 yuan.

Cement and agriculture shares were among  the biggest losers. Xinjiang Qingsong Building Materials and Chemicals (Group) Co shed 3.19 percent to 9.71 yuan. Agriculture company Fujian Sunner Development Co dropped 5.17 percent to 11.92 yuan.

A-shares are expected to see more short-term fluctuations as investors tend to lock in profits ahead of the Chinese New Year, said market watchers.