The network also said Al Franken, its best-known personality, would leave Feb. 14, replaced by Thom Hartmann, whose progressive talk show is currently syndicated.
Franken said on his program Monday he was leaving because he was considering running for U.S. Senate in his home state of Minnesota.
SLG is controlled by Stephen L. Green, founder and chairman of New York's SL Green Realty Corp. Green is also the brother of longtime New York Democratic politician Mark Green.
Green said he planned to "extend this special brand by partnering with other platforms beyond radio to make sure that Air America's content reaches the wide audience it deserves."
The sale, which must be approved by a bankruptcy court, is expected to close in mid-February, Air America parent Piquant LLC said. Piquant filed for Chapter 11 protection from creditors in October.
Air America is heard on 81 stations reaching 54 percent of the United States, as well as on XM satellite radio.