Here is the speculation (pardon me if I am not being original):
The Microsoft may take over the Nokia at any point now. The question arises: what are they waiting for?

The answer is that they are targeting the market with WF as an OEM product. This means they want to compete with Android/Apple, and for that they need Nokia, HTC, Samsung, LG and Chinese to start producing WF based devices.

If this is the case than buying Nokia officially is a bad move at the moment, because that will repulse the HW manufacturers.

My guess is that the Nokia is unofficially M$ already. This was not announced, but I believe that the shareholders of Nokia have
closed a deal before Elop came to Nokia.

The trade may not have been done publicly, but it would be worthy to investigate if major Nokia shareholders have somehow gained some stocks from certain other companies at that time.

The crucial message M$ is sending to HW manufacturers is:
We don't want to crush you, we want to crush Google/Android.

There is also the unspoken: We don't want to crush you (now), we will do it for later, once we crush Google/Android.