On January 25, China National Aviation Co (CNAC) will be de-listed from the Hong Kong Stock Exchange after its parent Air China Ltd completes a HK$3.23 billion buyout of the company.

Air China's cash offer for the shares it didn't already own in the unit got final government approval on January 23, Air China said in a statement to the Shanghai Stock Exchange.

The airline's purchase will raise its stake in Cathay Pacific Airways Ltd to 17.5 percent and may help Air China boost profit as it plans to work with Cathay Pacific on sales and operations.