Ewout Steenbergen
Executive Vice President and Chief Financial Officer at Booking
Thank you, Glenn, and good afternoon. I will now review our results for the second quarter and provide our thoughts for the third quarter and the full-year. All growth rates are on a year-over-year basis. Information regarding reconciliation of non-GAAP results to GAAP results can be found in our earnings release.
Now, let's move to our second quarter results. Our room nights in the second quarter grew 7%, which exceeded the high-end of our guidance by 1 percentage point. As expected, we saw room night growth moderate from the first quarter, as we saw less year-over-year expansion of the booking window in the second quarter. Looking at our room night growth by region, in the second quarter, Europe was up mid-single-digits, Asia was up mid-teens, rest of world was up high-single-digits and the U.S. was up mid-single-digits.
We continue to grow our alternative accommodations business faster than our overall business. For our alternative accommodations at Booking.com, our second quarter room night growth was 12% and the global mix of room nights was 36%, which was up 2 percentage points from the second quarter of 2023.
We continue to see encouraging progress in strengthening direct relationships with our travelers and increasing loyalty on our platforms. Over the last four quarters, the mix of our total room nights coming to us through the direct channel was in the mid-50% range, and when we exclude our B2B business, was in the low-60% range. We have seen both of these mixes continue to increase year-over-year. Mobile app mix of our total room nights was about 53%, which was up 6 percentage points from the second quarter of 2023. We continue to see that the significant majority of bookings received from our mobile apps come through the direct channel.
For our Genius loyalty program at Booking.com, we continue to see a year-over-year increase in the mix of room nights booked by travelers in the higher Genius tiers of Levels 2 and 3. These members booked more than half of the room nights over the past four quarters.
Outside of accommodations, we saw airline tickets booked on our platforms in the second quarter increase 28%, about in-line with our expectations, driven by the continued growth of flight offerings of Booking.com and Agoda. Second quarter gross bookings increased 4%, which was approximately 3 percentage points lower than the 7% room night growth due to about 2 percentage points of negative impact from changes in FX and about 1% lower constant-currency accommodation ADRs. The year-over-year ADR decline was negatively impacted by a higher mix of room nights from Asia. Excluding regional mix, constant-currency ADRs were about flat versus 2023.
While room night growth was above the high-end of our guidance range, gross bookings growth came in at the midpoint of our range due to about 2% lower constant-currency accommodation ADRs versus our expectation. In addition, our gross bookings were negatively impacted by lower flight ticket prices, in-line with the recent trends we have heard from many airlines.
Second quarter revenue of $5.9 billion grew 7% year-over-year, which exceeded the high-end of our guidance by 1 percentage point. Revenue growth was negatively impacted by about 2 percentage points from the change in Easter timing and 2 percentage points from changes in FX. Adjusting for these two items, revenue would have grown about 11%. Revenue as a percentage of gross bookings was 14.1%, which was slightly higher-than-expected due to a timing benefit, as we saw gross bookings growth decelerate in the quarter and a less expanded booking window than expected. Additionally, revenue associated with payments was higher-than-expected.
Marketing expense, which is a highly variable expense line, increased 8% year-over-year. Marketing expense as a percentage of gross bookings was 4.7%, about 15 basis points higher than the second quarter of 2023 due primarily to the timing of brand marketing spend as well as increased spend in social media channels. Second quarter adjusted sales and other expenses as a percentage of gross bookings was 1.9%, about 15 basis points higher than last year due to a higher merchant mix and higher transaction taxes. Our more fixed expenses on an adjusted basis were up 5% and were below our expectation across all three line items, personnel, G&A and IT. We're very focused on carefully managing the growth of our more fixed expenses and are taking actions to help improve our operating leverage in future quarters.
Adjusted EBITDA of $1.9 billion was above our expectations, largely driven by higher revenue and lower-than-expected fixed expenses. Adjusted EBITDA grew 7%, despite approximately 5 percentage points of pressure from Easter timing and 2 percentage points from changes in FX. Adjusting for these two items, adjusted EBITDA would have grown about 14%. When looking at our adjusted EBITDA margins for the first-half of 2024, which neutralizes the impact of the Easter timing shift, we're pleased to see 160 basis points of margin expansion versus the first-half of 2023.
Adjusted net income of over $1.4 billion was up 3%, slower than the growth in adjusted EBITDA due primarily to higher income tax expenses, which was impacted by some discrete items. Adjusted EPS of $41.90 per share was up 11% and benefited from a 7% lower average share count than the second quarter of 2023. On a GAAP basis, net income was over $1.5 billion in the second quarter.
Now, on to our cash and liquidity position. Our second quarter ending cash and investments balance of $16.8 billion was up versus our first quarter ending balance of $16.4 billion, due to about $2.4 billion of free cash flow generated in the quarter, partially offset by about $1.9 billion of capital return, including share repurchases and dividends.
Moving to our thoughts for the third quarter. We expect third quarter room night growth to be between 3% and 5%, a sequential deceleration as we expect the third quarter to benefit less from a year-over-year expansion of the booking window than we saw in the second quarter. For the third quarter, we expect the booking window to be more similar to last year. Additionally, we have seen a mild moderation in the market growth in Europe over the last couple of months, though our growth in Europe has remained stable from May through July, and we believe we continue to perform well relative to the market. We expect third quarter gross bookings growth to be between 2% and 4%, slightly below room night growth due to about 1 percentage point of negative impact from changes in FX.
We expect constant-currency ADRs to be down slightly year-over-year and for this to be offset by a slight benefit from flight bookings growth. While we continue to expect growth in flight bookings, we believe this will be less than previously expected due to lower flight ticket prices. We expect third quarter revenue growth to be between 2% and 4%. We expect third quarter adjusted EBITDA to be between about $3.25 billion and $3.35 billion, about flat year-over-year at the midpoint of the range. We expect adjusted EBITDA to grow slower than revenues due to deleverage from sales and other expenses and from growth in IT expenses related to higher software license fees and increased cloud cost. We expect third quarter revenue and adjusted EBITDA growth to also be negatively impacted by 1 percentage point from changes in FX.
In terms of our outlook for the full year, we're adjusting our gross bookings growth expectation to faster than 6%, which is a bit lower than our prior expectation due to less growth in flight gross bookings as a result of the lower flight ticket prices I previously mentioned. While flight prices have come down, we still expect strong growth in flight tickets for the year as we continue to expand the flight offerings at Booking.com and Agoda. We expect accommodation ADRs will be about flat to down slightly on a constant-currency basis.
For revenue, we now expect revenue growth of more than 7%, which is a bit higher than our prior guidance based on the outperformance in the first-half of the year and our expectation for higher revenue associated with payments. Revenue is impacted to a much lesser extent than gross bookings from the decline in flight ticket prices. We continue to expect about 1 percentage point of negative impact from changes in FX on our top-line growth rates. We're reducing our fixed opex growth expectation to low-double-digits, as we continue to focus on bringing this growth rate down over time. We expect adjusted EBITDA to grow in the high-single-digits, which is slightly faster growth than our prior expectation, given our outlook for increased revenue growth and lower fixed opex growth. We continue to expect adjusted EBITDA margins to expand year-over-year by a bit less than 8 percentage points. Finally, we're increasing our adjusted EPS growth expectation to above 15%.
In conclusion, we continue to expect 2024 to be a strong year for the Company. We remain focused on executing against our strategic initiatives, while taking actions to drive greater operating leverage. We're excited about our long-term vision for the Connected Trip and enhancing our offering through technology innovation, like Generative AI.
And with that, we will now take your questions. Operator, will you please open the lines?