Money seems to be the primary driver, news less so.
The top ten financial networks are likewise headed by Yahoo Business Network, Quicken Financial Network and Microsoft Investor. For comparison Quicken Financial gets 5.3 million, and Microsoft gets a distant 2.6 million. RelevantKnowledge's top 25 lists meanwhile show who's winning. ZDNet with 6.1 million. Amazon at 17th has 4.7 million, and CNN is 20th with 4.2 million.