Exxon Mobil Corp. said Friday that Chief Executive Rex Tillerson's total compensation rose 15% last year to $40.2 million.

Most of the increase was due to a change in pension value and other deferred compensation earnings, which rose to $13 million in 2012 from $9.8 million in 2011, the oil company said in a proxy report to shareholders.

Mr. Tillerson's salary rose slightly to $2.56 million, from $2.38 million in 2011. His bonus saw a slight bump up to $4.58 million from $4.368 million.

Stock awards for Mr. Tillerson rose to $19.62 million from $17.89 million in 2011.

Exxon, based in Irving, Texas, is the largest publicly traded oil company in the U.S.