Alibaba declined to comment. Yunda did not respond to a request for comment.
The move would mark another step forward in Alibaba's efforts to gain a bigger say in China's fragmented but fast-growing express delivery industry.
Domestic delivery firms dispatched 63 billion parcels last year, up 24% from 2018, while revenue grew 23% year-on-year to 745 billion yuan ($104.95 billion), data from the State Post Bureau showed in January.
But many firms are under pressure to boost logistics infrastructure and upgrade services to maintain market share as online retail continues to grow and amid continued price competition.