There were $3 trillion worth of corporate mergers in 2014. Comcast's proposed acquisition of fellow cable company Time Warner was the largest at $45 billion. Gene J. Puskar/AP hide caption

itoggle caption Gene J. Puskar/AP

The call center of Zappos.com gets high marks from consumers for strong customer service. Shashi Bellamkonda/Flickr hide caption

itoggle caption Shashi Bellamkonda/Flickr

Comcast is the largest cable company and home Internet service provider in the United States. Matt Rourke/AP hide caption

itoggle caption Matt Rourke/AP

An NBC store is seen through a window reflecting Rockefeller Center in New York City. Comcast, the nation's largest cable company, has owned 51 percent of NBCUniversal since 2011. Chris Hondros/Getty Images hide caption

itoggle caption Chris Hondros/Getty Images