DoorDash on Thursday announced it has agreed to buy Instacart in a $17 billion deal, combining the nation’s top grocery delivery app with a massive restaurant takeout service.

The deal – which is at least 75% cash, mostly financed by borrowing – values Instacart at $65 a share, a roughly 11% premium over its closing price on Wednesday, the companies said.

Shares of Instacart ticked up 0.3% premarket Thursday.

Instacart’s board of directors has unanimously approved the acquisition. Both companies are headquartered in San Francisco.

The massive takeover comes as Instacart’s annual revenue has been slowing amid stiff competition from Amazon and Walmart, both of which have expanded their same-day and next-day grocery delivery options.