Booking Holdings enjoyed progress in most of its financial and operating metrics during the first half of the year as its six primary properties -- Booking.com, Priceline.com, Kayak, Agoda.com, Rentalcars.com, and OpenTable.com -- contributed to increased inventory and higher bookings.
During the first quarter of 2018, revenue jumped 25.2% to $2.9 billion, propelled by nearly 197 million room nights sold during the quarter, an increase of 13% over the prior year. This increase can be traced to the ever-widening supply on the company's various hotel, car rental, and restaurant sites. For example, management reported that at the end of the first quarter, the organization's largest brand, Booking.com, had 28.2 million reported listings. As I discussed recently with my colleague Vincent Shen, Booking Holding's aggressive approach to inventory through frequent acquisitions supports its double-digit revenue growth rate, even as the company scales and matures.
Management also cited a higher return on investment in marketing channels, increased direct customer traffic, and mobile conversion as factors in the company's attractive current-year growth. While personnel costs and marketing expenses increased alongside revenue, Booking Holdings exhibited attractive operating leverage in the first three months of the year. Operating margin improved by 120 basis points, to 24.9%, against the first quarter of 2017.
Booking Holdings is also ensuring that it will remain competitive as the leisure market evolves. Alternative accommodation listings jumped 28% in the first quarter against the comparable quarter. The company now reports 5.2 million homes, apartments, and other alternative venues in its listings portfolio.
Booking Holdings will report on its second quarter of 2018 in mid-August. Management is projecting year-over-year growth in room nights booked of between 7% and 11%. Total gross travel bookings are expected to increase in a range from 10% to 14%.
Additionally, Booking Holdings sees second-quarter revenue expanding in a range of 11.5% to 15.5%. Net income per diluted share is scheduled to fall between $15.50 and $16.15. At the midpoint of this range, earnings per share would represent an advance of roughly 10% against the $14.39 earned in the second quarter of 2017.