The relative popularity of adjustable-rate mortgages (ARMs) and Öxed-rate mortgages (FRMs) varies considerably both across countries and over time. We ask how movements in current and expected future interest rates a§ect the share of ARMs in total mortgage issuance. Using a nine-country panel and instrumental variables methods, we present evidence that near-term (one-year) rational expectations of future movements in ARM rates do a§ect mortgage choice, particularly in more recent data since 2001. However longer-term (three-year) rational forecasts of ARM rates have a relatively weak e§ect, and the current spread between FRM and ARM rates also matters, suggesting that households are concerned with current interest costs as well as with lifet...