DoorDash is in advanced talks to acquire grocery-delivery rival Instacart in a deal that could value it at about $17 billion, according to reports from The Wall Street Journal and Reuters, citing people familiar with the matter.

A deal could come together as soon as this week, but there is no guarantee it will, and neither company has confirmed. Instacart’s earlier talks with Uber are no longer active, Reuters reports.

Instacart shares rose and DoorDash shares fell in Monday trading.