It may sound surprising, but a number of prominent real estate investors feel that now is the right time to purchase and develop rental apartment buildings rather than sell units as condominiums.

Last week, Ofer Yardeni and Joel Seiden, principals of Stonehenge Partners, closed on the purchase of a complex containing two 14-story elevator buildings and a 520,000-square-foot, two-story commercial building between 96th and 97th streets on Amsterdam Avenue. It has 418 residential units, a 38,000-square-foot garage, seven commercial spaces, and approximately 100,000 square feet of air rights. Stonehenge paid approximately $100 million for the property, which they are renaming Stonehenge Village, and obtained $60 million in financing from New York Community Bank. Matthew Kasindorf, of Meister Seelig & Fein LLP, represented Stonehenge. Stonehenge made another big residential acquisition in April: paying $240 million for the mixed-use Pennmark complex in the West 34th Street.

“Over the past 12 months, residential rents have increased by more than 20%, and the value of all of our properties has increased significantly,” Mr. Yardeni said. “Our long-term goal is to increase the rent roll and maintain the properties as long-term investments. The condo marketplace has created a need for quality market-rate rental buildings.”

Broad Street Development is also pursuing residential rental properties. In April, it paid $54.5 million to General Investment & Development Companies for 184 Thompson St., a nine-story, 140-unit apartment building with 10,000 square feet of retail space.

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Last week, the Related Companies announced plans to sell two of its residential towers. It’s expected to fetch close to $85 million for Columbus Green at 101 W. 87th St., an 18-year-old, 10-story, 95-unit rental tower with 14,000 square feet of retail that is less than a block from Central Park West. It’s also selling Parc Place at 225 Rector Place in Battery Park City, a 19-year-old, 23-story, 305-unit residential tower.

Both of these towers are expected to be sold to investors who will probably convert the properties into condominium and cooperative apartments. Both were built under the 80/20 program, which provides below-market rentals for 20% of the tenants, but they are no longer required to provide below-market units.

The Macklowe Organization is in the process of developing a residential condominium tower at the corner of 53rd Street and Second Avenue. Last week, it also announced plans to sell the RiverWalk, a 410-unit, high-end tower on the water off York Avenue and 72nd Street. The property is convenient to three major medical facilities and has excellent commercial space leased to medical tenants. The commercial space may be worth more than $100 million. The property could fetch close to $400 million.

The Aston, a 38-story, 266-unit rental apartment tower with 12,000 square feet of retail at 800 Sixth Ave., is expected to be sold by the middle of the summer. The property, which was completed in 2004, is subject to the 80/20 program, which remains in effect for at least 18 years. It will probably fetch close to $200 million. More than a dozen qualified suitors are pursuing the property.

“The market is finally producing a plethora of quality residential product to suit the long-standing pent-up demand of converters and long-term rental owners,” said Douglas Harmon, managing director of Eastdil. “For the first time perhaps in the last 20 years, there are more high-quality, large-scale residential buildings for sale than there are commercial properties,” said New York’s most active commercial and residential broker, who is handling the sale of the two Related buildings, the Macklowe building on East 72nd, and the Aston.

Last year, Jeffrey Levine, principal of Douglaston Development, began construction of a luxury residential rental building at 555 W. 23rd St. The building contains a total of 337 luxury one- to three-bedroom units. Mr. Levine and his partners had planned to develop the property as a rental building, with rents ranging from $2,700 to $5,300. The Sun has learned, however, that Mr. Levine and his partners have decided to sell the units as condominiums. They are expected to go for more than $1,300 a square foot.

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Few new residential rental buildings are under construction in Manhattan, except in Lower Manhattan, where developers have access to tax-exempt Liberty Bond financing. All of these developments utilize 80/20 bond financing.

Elsewhere, four residential projects are in different stages of development.

The Durst Organization is now renting its latest, the Helena, a 600,000-square-foot, 40-story building with 597 units at 601 W. 57th St.

The Durst Organization and Sidney Fetner Associates are developing a mixed-use, 58-story rental building at 125 W. 31st St., which will include a 77,000-square-foot condominium for the American Cancer Society. The ACS will open Manhattan’s first Hope Lodge in the building.

Another rental building will open this summer on the Lower East Side. Avalon Chrystie Place, at 229 Chrystie St., is a joint venture between the New York State Common Retirement Fund and AvalonBay Communities that will have 361 rental units and a 75,000-square-foot Whole Foods Market.

This summer, the first tenants will move into River East, a 196-unit apartment building at 408 E. 92nd St.

On the Upper East Side, the Related Companies is developing One Carnegie Hill at 215 E. 96th St. The lower portion of the residential tower will house rentals, and the top is under development as a condominium/cooperative tower. Over 75% of the condo units have been sold at prices in excess of $1,200 a square foot.

The Orion at 42nd Street between Ninth and 10th avenues was initially intended to have rental apartments on the lower floors. However, in March, the developers, Excell Investment and the Carlyle Group, decided to market all the units as condominiums. Yesterday, Excell and Carlyle entered into a contract to purchase the Hudson waterfront-Donald Trump Riverside South development on the West Side for $1.8 billion.

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A combination of factors has result ed in a lack of new rental apartment buildings in Manhattan. Land prices are now more than $300 per developable square foot, which combined with construction costs has made it financially unfeasible for developers to build rental apartment buildings. Nevertheless, investors will continue to seek out opportunities to purchase rental buildings and build new ones in the outer boroughs.

Mr. Stoler is a television broadcaster and vice president at First American Title Insurance Company of New York. He can be reached at mstoler@firstam.com.