According to the September 2016 PC operating system market share figures from Net Applications, the share held by Windows 10 actually went down slightly that month.
In August 2016, the first month after Microsoft ended its offer to let consumers update their old PC to Windows 10 for free, its market share was 22.99%. The numbers for September 2016 from Net Applications show that share dropped to 22.53%. While that is a tiny decrease, it's still a bit surprising, especially since there is evidence that Microsoft is still allowing owners of Windows 7 and 8.1 PCs to update to Windows 10 for free even if the offer has officially stopped.
Windows 7 stayed in first place in September's OS market share numbers with 48.27%, up from 47.25% in August. Windows 10 is in second place, and Windows XP, which Microsoft no longer supports, still remains in third place with 9.11%, down from 9.36% in August. Windows 8.1 is in fourth place with 7.83%, down from 7.92% in August. Windows 8, which Microsoft also no longer supports, had a PC OS share of 1.78% down from 1.82% in August.
In September, Microsoft stated that versions of Windows 10 were running on over 400 million active devices a month. However, the company did not break down how many of those devices were Windows 10 PCs and tablets.