Microsoft is under pressure as never before.Reaction to Windows 8 is at best mixed.
Millions of RT Surface devices lie unsold in warehouses.
Nokia isn't selling nearly enough Windows Mobile smartphones.
First quarter 2013 revenue was down eight percent.
Profits are dwindling fast.
And now there's been dramatic share sell-off.
It puts even more pressure on Ballmer's company-wide reorganisation, which amounts to one of the biggest upheavals since Microsoft's inception in 1972.
Read more Microsoft analysis posts.