BEIJING— Alibaba Group Holding Ltd. has become the majority owner of its logistics affiliate, a move that could allay concerns over financial transparency that drew the attention of U.S. securities regulators last year.

Alibaba is investing 5.3 billion yuan ($800.8 million) to raise its stake to 51% from 47% in Cainiao Smart Logistics Network Ltd. It will also invest 100 billion yuan ($15.11 billion) over the next five years to build up its global-logistics infrastructure and development of robots sorting and fulfilling merchandise.

Cainiao helps online merchants choose from among 15 delivery firms by providing information on cost and delivery time. About 70% of Cainiao shipments are routed by algorithms to ensure the network’s two million couriers get packages to customers as efficiently as possible.

Alibaba said the additional investment is part of its strategy to create a “seamless experience for shoppers.” The company said it aims to fulfill orders in China within 24 hours, and within 72 hours anywhere in the world.

A person familiar with Alibaba’s move said an inquiry by the Securities and Exchange Commission had no bearing on the company’s action. Alibaba disclosed the inquiry in May 2016 and said it was cooperating with authorities. The SEC doesn’t comment on individual companies it is examining.