Chinese shares experienced another day of drastic volatility on Wednesday.

The benchmark Shanghai Composite Index once surged over 2 percent in the trading session, but the gains quickly narrowed in the afternoon, with the index up only 0.65 percent to end the day at 4,446.29 points.

The Shenzhen Component Index gained 1.39 percent, or 209.71 points, to close at 15,337.08 points. Total turnover on the two bourses came in at 1.65 trillion yuan (270.5 billion U.S. dollars).

The ChiNext Index, tracking China's Nasdaq-style board of growth enterprises, surged 2.51 percent, or 83.51 points, to end at 3,406.28 points.

Artificial Intelligence, software, 3D printing, and ship building industries were among the day's biggest winners.

The telecommunication sector rose by nearly 5 percent on news that the government will invest hundreds of billions of yuan in the coming years to boost Internet speed.

The country plans to spend more than 430 billion yuan (70.4 billion U.S. dollars) in 2015 and more than 700 billion yuan total in 2016 and 2017 to promote network construction, according to a guideline issued by the State Council, China's cabinet, on Wednesday morning.

Buoyed by the news, Guomai Tech surged by the daily limit of 10 percent to end the day 16.67 yuan.

To better reflect stock market performance, the Shenzhen Stock Exchange started sampling 500 of 1,687 public companies on Wednesday for the Shenzhen Component Index, up from 40 firms previously.