The company had already announced that most likely, this fine was coming. Now that it came, it turned an uncertainly into reality, so… no more uncertainty, and thus, stock price goes up.
Now, the scale of the fine is really a separate topic, so intertwining the two is not something I would have done. If anyone cares, my take is that fines like this against corporations are indeed nothing more than a cost of doing business; not that big a deal. Real teeth need to be put into such fines, such as the second offense would see the fine increase in orders of magnitude, or the company getting broken up. Or executives being indicted and sent to jail.
