For much of its existence, KKOB-FM had an adult contemporary or hot adult contemporary format. KKOB-FM's first shift to mainstream top 40 came in 1999, playing "Today's Best Music", rivaling the newly launched KCHQ-FM, "Channel 105.1", which returned the top 40 format to the market after a six-year absence. Both stations were often head-to-head in the ratings until late 2000, when KCHQ had shifted to an 80s hits format. However, in January 2001, KKOB would also switch to an 80s format, putting the two stations in competition once again. KKSS, which had been facing a fierce rhythmic battle with KYLZ-FM, would become the area's mainstream top 40 outlet a few weeks later, but in November 2002, KKSS was sold to Hispanic Broadcasting and had returned to rhythmic top 40. KCHQ had dropped the 80s format in the Fall of 2001, but the format continued to lose steam on KKOB. Therefore, on Christmas Day, 2002, KKOB-FM would return to the top 40 format and had also returned to using the three-letter 'KOB' ID in its branding.