'Not gonna happen,' some say.

Both Hitwise and comScore issued additional data this week on what sort of market player would be formed with a merger of Yahoo and Microsoft's MSN.

The data considers reach of online properties, the search market, email and instant messaging, among others, reports MarketingCharts.

From Hitwise's research director, Heather Dougherty, data for the week ended Jan. 26:

• Both yahoo.com and msn.com retain traffic - 93 percent of visitors to yahoo.com and 89 percent of those to msn.com were return visitors from the previous 30 days.
• Both Yahoo and MSN attract much traffic to their front pages and send it to other properties in their networks:
  • Yahoo.com, ranked 4th in visits among all categories, sends 65.78 percent of its traffic (based upon the top 100 websites) to other Yahoo properties.
  • MSN.com, ranked 8th in visits among all categories, sends 52.43 percent of its traffic to other MSN properties.

• Web-based email services and search are the top destinations for the traffic from both portals: the combined traffic to these categories from yahoo.com and msn.com were 47 percent and 31 percent, respectively.
• Email sends traffic back: Yahoo Mail and Windows Live Mail each sent 12 percent of downstream traffic back to their network front pages.

From a comScore media advisory:

• Google Sites had nearly 588 million visitors worldwide in December 2007, more than both Microsoft Sites and Yahoo Sites individually, but less than the combined audience of Microsoft and Yahoo, which would reach 665 million worldwide visitors.

• In search share, Google Sites lead both the US (58.4 percent share), and worldwide (62.4 percent share). Microsoft/Yahoo combined would have a 32.7 percent US search share, and a 15.7 percent share worldwide.

• In display ad share, Microsoft/Yahoo would overwhelm Google.

• In the email category, Yahoo mail leads both in the US (82 million visitors) and worldwide (257 million visitors).

• A Microsoft/Yahoo combined instant messenger audience of 298 million would reach nearly 77 percent of the instant messenger audience worldwide.