In a matter of five hours, the US delivery firm DoorDash Inc. announced two multibillion-dollar acquisitions that stand to turn what is already the largest food-delivery service in the US into a formidable global player.

DoorDash has agreed to purchase British food and grocery delivery service Deliveroo for $3.9 billion, the companies have revealed in a filing with the London Stock Exchange. The acquisition will "strengthen DoorDash's position as a leading global platform,

The combined group will have a global presence in over 40 countries, serving around 50 million monthly active users, the companies said.