Good news, bad news. While the total number of foreclosures filed in the city fell last month from year-earlier levels, the number of co-op units scheduled for foreclosure spiked to its highest level in two years, according data released Wednesday by PropertyShark.com

In May, co-op apartments made up 79% of all new foreclosure auctions scheduled. Some 90 co-op apartments were in foreclosure, 15 times more than the same time last year. That May total was also up 34% from the previous month.

In contrast to that unusual spike, new foreclosures for residential units as a whole, including condos and single-and-two family homes, across New York City actually dropped 38% last month from the same month a year ago.

“If we get another month or two of higher number of co-op foreclosures, then it will be something to look into,” said Matthew Haines, founder of PropertyShark.com, adding that it could just be a one-time blip in the data. Co-op lawyers and other industry experts have not observed any unusual activity among co-ops and could not explain the rise.

According to PropertyShark.com, the co-ops scheduled for foreclosure were mostly in Manhattan and Queens, where there were 32, and 36, respectively. A majority of the foreclosures were initiated by banks; only seven were led by co-op boards.

Manhattan was the only borough to see a rise in foreclosures last month. It recorded 32 new foreclosures, 10 times higher than in May 2010. The other boroughs all saw significant drops. In Brooklyn new foreclosures dipped 9%, in Queens 45%, in the Bronx 76%, and Staten Island a whopping 90%.

The declines are largely a result of a drop in single- and two-family home foreclosures, noted Mr. Haines, but that does not mean that the market has stabilized. Instead he attributed some of the drop to legal and regulatory rules that are delaying the number of new foreclosures filed. Last month, the number of foreclosures for single and two-family homes fell 88% to 21 from the same time a year ago.

“This downward movement is not because of a change in economic situation. Things are not any better,” he said, predicting that foreclosures may begin to rise as soon as six months. “We’ve seen a temporary slowdown of the processing of foreclosures.”