Tesla's stock has been rallying, but there's no clear reason why

Over the course of 2016, Tesla shares had slid over 15%.

They're still down, but since last week, the stock has staged a moderate rally. It was trading up over 6% to $208.

Is there an obvious catalyst for this move?

Not really. Tesla did recently institute a "idle" fee for its Supercharger network to discourage owners from spending too much time parked after charging. But the company doesn't expect to make money off the shift.

Tesla has also increased some of its credit lines, which perhaps indicated that the company won't return to the capital markets next year.

That could be driving an upsurge in investor confidence.

In the past, Tesla shares have entered a volatile period as one year ends and the next begins. This was usually driven by the awareness that the automaker wouldn't exceed its guidance on vehicle deliveries for the year.

This year, it looks as if Tesla will come it at the low end of its guidance of 80,000 to 90,000 deliveries.

The markets should have already priced that it, which makes this little pre-holiday Tesla rally all the more interesting. CEO Elon Musk will probably take it.