Hong Kong is the world’s most expensive city to live in as an expat for the second year in a row, according to a new study. New York and Geneva took second and third place in the rankings.

Higher prices and a stronger currency over the past year kept the Asian city at the top of the tree, according to ECA International, which carried out its research in March. London and Tokyo round out the top five.

Soaring rental costs were part of the reason London and New York took their positions in the top five, with rent in those cities rising 20% and 12% respectively...