Shares of logistics heavyweights UPS and FedEx tumbled on Monday after Amazon unveiled plans to open its supply chain network to outside businesses.

Both stocks were down 10 per cent by midday.

The companies did not immediately respond to requests for comment, while Amazon’s shares were largely flat.

The tech giant’s new offering, “Amazon Supply Chain Services,” will enable companies across various industries to tap into Amazon’s logistics infrastructure to transport and deliver products and raw materials.

The move marks another step in Amazon’s expanding services business and positions the company as a formidable competitor to UPS and FedEx.

It will open up Amazon’s fleet of more than 100 cargo planes and its vast warehouse network to outside clients.

Amazon said major retailers, including Procter & Gamble, 3M, Lands’ End and American Eagle Outfitters, have already enrolled in the new program.