Wednesday, Expedia announced the acquisition of buy vacation rental site HomeAway for about $3.9 billion in cash and stock. And announced that HomeAway will operate autonomously.

Expedia expects the transaction to close in the first quarter of 2016. The announced deal is the biggest acquisition in Expedia’s history, comparing to deals in which the company bought Orbitz Worldwide for $1.3 billion and Travelocity for $280 million.

HomeAway’s business model is a bit different from that of Airbnb, which lets homeowners add listings for free but charges travelers a service fee and the transactions happen on site.