25 of the most generous companies in America

Each year, The Chronicle of Philanthropy gathers data on charitable giving in corporate America.

The Chronicle, an organization dedicated to advising and reporting on nonprofits, determines its annual list of the most generous companies by ranking the largest Fortune 500 companies on the amount of total donations given - including both cash and product donations - for the fiscal year.

This year's corporate giving report reveals that America's largest companies increased cash donations by 2% in 2015, largely led by gifts from banks and drug companies. Pfizer and Gilead Sciences topped the list, with more than $3 billion and $2 billion, respectively, in total donations last year.

Though The Chronicle sought to include data for the 150 largest companies on the Fortune 500, two organizations - Berkshire Hathaway and Fannie Mae - said they do not make charitable grants, and an additional 81 companies either declined to provide data or did not respond to repeated requests.

Read on to find out which of America's largest corporations made the most philanthropic donations in 2015.