Airbnb has completed its acquisition of the last-minute hotel booking application, HotelTonight, the company announced on Monday. The deal is Airbnb’s largest M&A transaction yet, and will accelerate the home-sharing giant’s growth as it gears up for an initial public offering.

Airbnb reportedly began talks to acquire HotelTonight months ago, and finally confirmed its intent to acquire the business in early March. Reports indicated a price tag of more than $400 million; Airbnb declined to comment on the size of the deal.

As part of the deal, HotelTonight co-founder and chief executive officer Sam Shank will lead the boutique hotel category at Airbnb, one of the company’s newer units meant to help it scale beyond treehouses and quirky homes.

“When we founded HotelTonight, we sought to reimagine the hotel booking experience to be more simple, fast and fun, and to better connect travelers with the world’s best boutique and independent hotels,” Shank said in a statement. “We are delighted to take this vision to new heights as part of Airbnb.”

Shank launched the San Francisco-based company in 2010. Most recently, it was valued at $463 million with a $37 million Series E funding in 2017, according to PitchBook. HotelTonight raised a total of $131 million in equity funding from venture capital firms including Accel, Battery Ventures, Forerunner Ventures and First Round Capital.