HONG KONG—The normal summertime surge in demand for high-end apartments in Hong Kong's top neighborhoods was weak again this year as companies changed the way they pay for housing for their expatriate employees and the finance sector continued to struggle.

A shift away from banking and toward retail and other sectors, among companies relocating staff, has pushed down demand. Hong Kong's efforts to cool its housing sector have weighed on the market as well.

Expatriate families relocating to Hong Kong, the main prospective tenants for high-end leases above 80,000 Hong Kong dollars (US$10,300) a month, usually move in the summer months before the school year begins. The start of the third quarter is the "traditional busy time" in the high-end leasing market, according to Edina Wong, senior director of residential leasing at Savills , a real-estate consultancy company. This year, "there's been a minor bump, but not as big as previous years'."

It hasn't been nearly enough to make up for the longer trend: a decline in luxury rental demand by 30% to 40% over the past two years, according to Ms. Wong. "It's a huge drop," she said. "The higher the rental, the quieter it is."