HANGZHOU, Aug. 1 (Xinhua) -- Chinese e-commerce powerhouse Alibaba and delivery company STO Express signed an agreement on a stake purchase option Wednesday.

According to a statement released by STO, Alibaba is granted the option to purchase stakes within three years from Dec. 28, with an estimated total purchase price of 9.98 billion yuan (about 1.45 billion U.S. dollars).

Some market participants said arrangement of stock options is one of the most common forms of investment and Alibaba's investment in STO will raise awareness in the market that the express industry is a core asset for e-commerce companies.

Alibaba's delivery arm, Cainiao Network, has cooperated with several express companies in the logistics field with its technological and resource advantages. The company has invested in courier giants including Best Express, ZTO Express and YTO Express.