Coca-Cola's archrival PepsiCo declined to sponsor American Idol at the show's start. What the Los Angeles Times later called "missing one of the biggest marketing opportunities in a generation" contributed to Pepsi losing market share, by 2010 falling to third place from second in the United States. PepsiCo sponsored the American version of Cowell's The X Factor in hopes of not repeating its Idol mistake until its cancellation.
Which major drink manufacturer decided at the beginning of American Idol not to be a sponsor? 
PepsiCo