Shanghai's pre-owned housing index fell in June for the first time in two years because nearly half of the areas tracked saw prices decline.

The index, which monitors price changes of pre-owned homes, dipped 0.05 percent, or 2 points, from May to 2,955 last month, ending a 24-month rally, the Shanghai Existing House Index Office said yesterday.

"Tightened credit, an inadequate supply of existing houses as well as high inventory of new homes all damped buyers' momentum," said Chen Zhen from the index office. "However, unlike real estate developers to whom cash flow is really important, individual homeowners often do not have incentives to offer large discounts to attract buyers, so we don't expect major price declines despite the sluggish sentiment."

As of June, there were around 102,600 pre-owned homes available for sale across the city, a four-year low. The inventory of pre-owned apartments with an area no bigger than 100 square meters saw the sharpest decline, the office said.

The prices of pre-owned houses fell in 64 of the 130 areas tracked by the office while those in 42 were flat from a month ago. That compared with 42 and 36 areas, respectively, in May.

The supply of new homes in Shanghai has exceeded a historic high of 11 million square meters, according to latest data on the city's official real estate website.