The companies that spend the most on advertising, on any platform, must first be ones that have the money to do so. Next, they need to be relevant to that medium – if you are an online entity, it would make the most sense for you to go where your customers are and find them at their decision points.
That said, here is the most recent information I have been able to find on the top Advertisers for Google
ESTIMATED 2013 U.S. SPENDING ON DESKTOP SEARCH ADS ON GOOGLE PROPERTIES. FIGURES EXCLUDE MOBILE SEARCH ADS AND PRODUCT LISTING ADS. FIGURES ALSO EXCLUDE SEARCH ADS SHOWN ON THIRD-PARTY PROPERTIES THAT USE GOOGLE AS SEARCH ENGINE.
Originally Posted: https://www.quora.com/Which-companies-are-among-Googles-top-advertisers
Originally Posted On: 2016-02-11