The question of search engine bias can be easily verified by examining search results for popular words and phrases. I have performed search for very competitive and frequently searched word finance on Google and Yahoo.
As I expected Google lists as number one:
Google Finance offers a broad range of information about stocks, mutual funds, public and private companies. In addition, Google Finance offers interactive ... finance.google.com
And Yahoo shows in top position... no surpise here:
Free sharemarket information, financial news, glossaries and guides to help you learn about Australian and international markets.
See if you can find other examples of search engine bias.