China's biggest e-commerce provider, Alibaba Group Holdings, has come to a $7.1bn agreement after years of negotiations with Yahoo! to buy back half the 40 percent share owned by the American internet giant, the companies have announced.

As part of the agreement, Yahoo! will sell half its stake for an estimated $6.3bn in cash and $800m in new Alibaba preferred stock. It is believed the purchase could pave the way for Alibaba to pursue an IPO within the next 18 months.

Alibaba Group is currently valued at $30-35bn and is expected to raise the money through a mix of cash, debt and equity.