The Mark & Kim Morning Show was one of the longest-running shows on Los Angeles radio, airing for more than 20 years until ending in 2007. AMFM/Clear Channel/iHeartMedia era In September 1999, Cox Communications swapped KOST and sister station KFI with AMFM, Inc. for 14 stations in several East Coast markets. AMFM was then purchased by Clear Channel Communications in 2000. (In 2014, the company's name was changed to iHeartMedia, Inc.) Over the years, particularly in the late 2000s and into the 2010s, the station would shift to a more upbeat mainstream AC format. Despite the changes, KOST has continued to garner solid ratings. Christmas music has been aired from early November through Christmas Day since 2001. KOST experienced little air staff turnover until the 2000s. On November 29, 2007, morning show co-host Kim Amidon departed the station. This was followed by KOST's original midday host Mike Sakellarides (who moved on to KTWV) and longtime traffic reporter Mike Nolan (who was eventually rehired at KOST). In October 2008, former KYXY San Diego radio personality Kristin Cruz joined Mark Wallengren as co-host of KOST's morning show. Cruz left the station in May 2014. In 2009, the midday shift was voice-tracked by former WLTW New York City personality Karen Carson. In February 2011, Carson resigned to join CBS Radio-owned WWFS in New York. Both Christine Martindale (2 days per week) and Ted Ziegenbusch (3 days per week) filled in on the midday show until August 2011, when former KBIG midday host Kari Steele took over. Steele now hosts KOST's public affairs program The Sunday Journal broadcasting every Sunday following Animal Radio, providing interviews with community organizations. Also in August, longtime KOST afternoon personality Bryan Simmons left KOST. Simmons had been on the station since 1982, except between 2002 and 2004, when he hosted the Boogie Nights show at KBIG. Ted Ziegenbusch filled in for several months after Simmons departed. In December 2012, Christine Martindale was among the radio personalities laid off from Clear Channel stations. On January 17, 2013, it was announced that Martindale would join KKGO (105.1); her first day at Go Country 105 was February 4. Ellen K, a former co-host on the KIIS-FM morning show and On Air with Ryan Seacrest, took over the KOST morning show on October 19, 2015. Mark Wallengren, who had been part of the KOST morning show since 1986, moved to afternoons, replacing Bruce