Phillips began exchanging stock for securities.

The Bartlesville, Okla.-based firm said it began repurchasing 72.58 million shares of its stock with securities valued at $62 a share, a move that is enabling the nation’s eighth-largest oil company to remain independent at a cost of increasing its debt by $4.5 billion. After Phillips Petroleum made the offer to exchange nearly half of its stock for notes and bonds early this month, financier Carl Icahn agreed to drop his hostile takeover bid for the company.