| Microsoft | Nov-8 | Dec-10 | Jan-11 | Feb-11 | Mar-11 | Apr-11 | May-11 | June-11 | July-11 | Aug-11 | Sept-11 |
| US installed base | 9 | 8.4 | 8 | 7.7 | 7.5 | 6.7 | 5.8 | 5.8 | 5.7 | 5.7 | 5.6 |
| Percent loss | 0.7 | 0.6 | 0.4 | 0.3 | 0.2 | 0.8 | 0.9 | 0 | 0.1 | 0 | 0.1 |
Comscore have released their monthly US cellphone subscriber market share numbers, and once again Windows Phone is in a holding pattern.
The platform added another 75,000 users, for a total of 4.89 million Windows Phone (Windows Mobile + Windows Phone 7) users in USA.
On the other hand, instead of the upturn in market share we were hoping far last month, there was once again a small drop in market share, with Windows Phone now having 5.6% of the installed base.
As usual, at least we are not RIM, which lost 0.8% market share and 136,000 users. We will look forward to November’s numbers, due in December, to see if there is a bounce in market share due to the introduction of new handsets and new marketing efforts by Microsoft.