ZTO Express Inc, the Chinese delivery service that gets most of its business from Alibaba Holding Group Ltd, fell in its trading debut after raising the biggest U. initial public offering this year.

ZTO shares open at $18.40.

ZTO shares dropped to $18.19 at 10:33 a.m. in New York after opening at $18.40. The company raised $1.4 billion by selling 72.1 million American depositary shares at $19.50 apiece, according to a statement, after offering them for $16.50 to $18.50 each.

Alibaba, which uses ZTO to fulfill orders, accounted for 75 percent of ZTO's parcel volume in the first half of this year. The company's IPO comes days before Alibaba reports earnings and weeks before its Singles' Day promotion, which is expected to surpass last year's record $14.3 billion in sales.

The offering will distinguish the Shanghai-based company internationally from its domestic rivals. STO Express and YTO Express have unveiled plans to go public through reverse mergers, while the country's biggest player, SF Express, received conditional approval to list in a similar way in Shenzhen.

Morgan Stanley and Goldman Sachs Group Inc. led the offering. The shares are trading on the New York Stock Exchange under the symbol ZTO.

Founded in 2002, ZTO is a major player in China's quickly expanding e-commerce market. It delivers parcels for Alibaba and JD.com Inc, among others.

ZTO will use the proceeds from its offering to buy more trucks, expand capacity through the purchase of land, facilities and equipment, and for other general corporate purposes.