China Evergrande Group, the country's largest property developer, stepped up a buying spree of shares in rival China Vanke Co Ltd in the weeks after a warning from the Shenzhen Stock Exchange that it is closely monitoring Evergrande's investments in listed companies.

Evergrande boosted its stake in Vanke to 14.1 percent, bringing its total expenditure on Vanke's A-shares to about 36.3 billion yuan ($5.3 billion), according to a regulatory filing on Tuesday. The Guangzhou-based home builder bought a further 509.8 million A-shares on the market and through block trades from Nov 18 to 29, the company said.

Vanke's A-shares rose 3.13 percent to close at 26.98 yuan per share in Shenzhen on Wednesday. The shares have surged more than 50 percent since early August, when Evergrande first disclosed a stake in the developer.