(Yicai Global) Sept. 27 -- China's National Development and Reform Commission has fined six listed chemical companies a total of CNY100 million (USD15 million) for reaching monopolistic agreements with competitors through social media and messaging platform WeChat.

Sichuan Jinlu Group Co. [SHE:000510] and Inner Mongolia Junzheng Energy & Chemical Group Co. [SHA:601216] were among recipients of the penalty, Securities Daily reported today.

Executives at the firms created a WeChat group to communicate with each other after they met at an industrial conference in May 2016. After discussing their sales price for PVC products, the agreed on a factory price of USD761.16 per ton.

The executives then raised their prices to the negotiated amount, talked further, and continued to hike prices.

The firms' agreement to fix commodity prices through electronic communication constitutes an illegal price monopoly, the regulator said, after conducting an anti-trust investigation this year. The USD15-million penalty is equal to 1 percent of the companies' sales of PVC products last year.