A group of 18 condominiums in an Uptown building were sold by their individual owners to a company that will operate the units as rentals.

It’s the latest in a string of deconversions of former condo buildings, as groups of homeowners cooperate to unload their condos in bulk to investors who operate them as apartments. In July, two North Side buildings containing a total of 34 units went for a combined $12.2 million.

In Uptown, the purchase price for the block of 18 units in a 20-unit building on Sunnyside Avenue was just over $4.3 million, according to Lee Kiser, the Kiser Group managing broker who represented the condos for their owners. The price works out to an average of $239,000 per condo, which Kiser said was “significantly more than any of them would get if they’d been sold alone.”

The last recorded sale in the building was a three-bedroom unit that went for $192,000 in August 2013, according to the Cook County recorder of deeds. That transaction was a short sale, in which a lender agrees to let a homeowner sell for less than the amount owed on the mortgage.

The block of units was on the market less than a week in May before it went under contract, Kiser said. The buyer was Uptown-based Seminary Properties. Seminary principal Sam Martin said his firm has owned a rental building on the same block for a dozen years and “we feel good about this neighborhood, so we bought” the 18 condos. It was his firm’s first purchase of a deconversion prospect, he said.

While Illinois’ condo law requires all unit owners to abide by a vote of 75 percent or more of the building’s owners, the owners of two units in the building voted against the move, and their condos were not sold in the Aug. 15 transaction. Martin said he could not comment on the status of the remaining two units.

Half of the 18 units were already being operated as rentals by their owners, who because of sagging home prices were unable to sell when they moved to new homes, Kiser said. Seminary re-leased those units to their occupants, Martin said, and so far has rented five more, with four units left to rent. Seminary did not raise the rents on any of the units, Martin said.

Most units in the 97-year-old brick building are one-bedrooms, Kiser said. It was converted to condominiums from apartments sometime in 2003, according to the Cook County recorder of deeds.