Microsoft sites enjoyed a 24% increase in total unique visitors from 34.7 million in November 2009 to 43.2 million in November 2010, according to comScore.
Google sites came a close second with 40.3 million users in November 2010, although only saw a small 4% increase in total unique visitors during the one-year period.
Facebook, meanwhile, posted a smaller 3% rise in visitors – its total unique visitor numbers were up to 33.3 million at the end of last year.
Read the full NMA article here.