Pension contributions by S&P 500 companies increased to $65 billion last year from $40.6 billion in 2002, according to a new Wilshire Associates study. Excluding General Motors Corp., Detroit, which contributed $18.6 billion last year and $4.9 billion in 2002, contributions were $46.4 billion in 2003, up from $35.7 billion the year before. Also, 81% of S&P 500 company pension plans were underfunded as of Dec. 31, down from 89% a year earlier. The funding ratio of these plans rose to 89% in 2003 from 83% in 2002, as defined benefit assets for S&P 500 companies rose $139 billion to $1.03 trillion, while liabilities rose $85 billion to $1.15 trillion, according to the annual survey. The median corporate funded ratio reached 82% for 2003, up from 78% a year earlier. The median investment return last year was 17.1%, compared with a loss of 9% in 2002. The median discount rate used to value liabilities fell to 6.25% from 6.75%, causing an additional 6% increase in reported pension liabilities, according to Wilshire.