(Reuter) - Online travel agency Booking Holdings ( BKNG ) forecast lower room nights growth in the third quarter after beating analysts' estimates for second-quarter revenue and profit, sending its shares down 8% after the bell.

The booking window shrank in the second quarter and is expected to shrink further in the third quarter, the parent of booking.com and priceline brands said on a post-earnings call.

Booking window, an important metric in the travel industry, refers to the number of days between the reservation date and actual arrival. A higher booking window indicates strong occupancy and revenue guaranteed in advance.

The company forecast third-quarter room night growth to be between 3% to 5%, compared to 7.1% growth in the second quarter and 14.9% growth in the year-ago quarter.

Booking reported a quarterly adjusted profit of $41.90 per share, compared with analysts' estimates of $38.37.

Total revenue rose 7% to $5.86 billion for the quarter ended June 30. Analysts had expected revenue of $5.77 billion, as per LSEG data.

(Reporting by Aishwarya Jain; Editing by Sriraj Kalluvila)