Just Eat has agreed a deal with Takeaway.com to merge and form one of the worlds largest food delivery firms.
The joint group would be valued at £8.2 billion, and bring together businesses that process 360 annual million orders worth £6.6 billion.
Just Eats shares opened almost 25% up on Monday, at 785p.
If the deal goes through, Just Eat shareholders will retain just over half of the combined group, with Takeaway.com shareholders taking a 47.8% stake.