Other income (expense), net increased by $3.1 million, or (105)%, for the three months ended September 30, 2021, compared to the three months ended September 30, 2020, due primarily to the increase in the fair value of our warrant derivative liabilities that occurred during the three months ended September 30, 2020.
Nine Months Ended September 30, 2021 Compared with the Same Period in 2020
Interest income decreased by $(0.3) million, or (92)%, for the nine months ended September 30, 2021, compared to the nine months ended September 30, 2020, due primarily to the decrease in cash and cash equivalents held in income generating accounts.
Interest expense increased by $(4.4) million, or 93%, for the nine months ended September 30, 2021, compared to the nine months ended September 30, 2020, due primarily to the increase in total borrowings outstanding during the periods. In May 2020, we issued the D-1 Convertible Notes, which contributed to the overall increase year over year.
Other income (expense), net increased by $(5.8) million, or 133%, for the nine months ended September 30, 2021, compared to the nine months ended September 30, 2020, due primarily to the increase in the fair value of our warrant derivative liabilities.
Key Business Metrics and Non-GAAP Financial Measures
We track the following key business metrics and non-GAAP financial measures to evaluate our performance, identify trends, formulate financial projections, and make strategic decisions. Accordingly, we believe that these key business metrics and non-GAAP financial measures provide useful information to investors and others in understanding and evaluating our results of operations in the same manner as our management team. These key business metrics and non-GAAP financial measures are presented for supplemental informational purposes only, should not be considered a substitute for financial information presented in accordance with GAAP, and may be different from similarly titled metrics or measures presented by other companies.
| | | | | | | | | | | | |
| | Three Months Ended September 30, | | Nine Months Ended September 30, |
| | 2021 | | 2020 | | 2021 | | 2020 |
|
| | (in thousands, except GBV per Night Sold) |
Gross booking value ("GBV") | | $ | 776,150 | | $ | 393,571 | | $ | 1,536,228 | | $ | 742,360 |
Nights sold | | | 1,840 | | | 1,113 | | | 4,071 | | | 2,301 |
GBV per Night Sold | | $ | 422 | | $ | 354 | | $ | 377 | | $ | 323 |
Gross Booking Value
Gross Booking Value (“GBV”) represents the dollar value of bookings from our distribution partners as well as those booked directly on our platform related to Nights Sold during the period and cancellation fees for bookings cancelled during the period (which may relate to bookings made during prior periods). GBV is inclusive of amounts charged to guests for rent, fees, and the estimated taxes a guest pays when we are responsible for collecting tax.
Growth in GBV reflects our ability to attract homeowners, either through means of individual additions, portfolio transactions or strategic acquisitions, retain homeowners and guests, optimize the availability and sale throughput of nights inventory, and reflects growth in Nights Sold and the pricing of rents, fees, and estimated taxes a guest pays.
Through the three months ended September 30, 2021, GBV has increased to $776.2 million, a 97% increase compared to the same period in 2020. Through the nine months ended September 30, 2021, GBV has increased to $1,536.2 million, a 107% increase compared to the same period in 2020. The increases were primarily driven by growth of new homes and Nights Sold.
We experience seasonality in our GBV that is consistent with the seasonality of Nights Sold as described below. As we continue to add new homes to our platform, optimize their pricing and distribution, retain homeowners and guests, and grow Nights Sold, we expect Gross Booking Value to continue to grow.