Alaska Air will buy 18% of Jet America’s shares.

Alaska Air Group, in the midst of a bidding war for ownership of Jet America, said it has exercised an option to purchase 18% of the California carrier at $3.25 a share. Alaska Air, based in Seattle, launched a $14.3-million tender offer for Jet America two weeks ago after getting the endorsement of Jet America’s management and directors. On Monday, Atlanta-based Delta Air Lines entered the bidding, offering $18.7 million for the Long Beach company.