Although we don't believe in timing the market or panicking over market movements, we do like to keep an eye on big changes -- just in case they're material to our investing thesis.

What: Shares of electric-car maker Tesla (NASDAQ:TSLA) are revving as much as 4.3% higher today. The company issued a press release today announcing expansion of its Supercharger network in Europe.

So what: The expansion of the network enables free and convenient long-distance travel between the Netherlands, Germany, Switzerland, and Austria. There are now 80 Supercharger stations worldwide, of which 14 are in Europe (four of them in Germany).

Tesla anticipates that by the end of March 2014, over 50% of the German population will live within 320 kilometers of a Supercharger -- and that by the end of the year 100% will be covered. According to Tesla's website, the company plans to eventually allow battery swaps at its stations for a fully charged battery in less than half the time it would normally take to refill a gas tank.

Now what: Tesla currently relies on word of mouth to stoke demand; the company does not advertise its products. Recently Tesla announced that it saw 6,900 deliveries in the fourth quarter, well above the estimate of 6,000. With production accelerating, it's important that Tesla continues to build out the infrastructure that is vital to supporting the increase in demand.

CEO Elon Musk mentioned in the last conference call that some of the company's European customers have been waiting two to three years for delivery. The European market is a significant market for the company in the long term. When Tesla reports earnings next month, look for further updates regarding European deliveries and orders. As for the stock itself, Tesla looks a bit pricey at 115 times next year's earnings estimates, but those estimates are on the rise. Tesla's demand and production growth is strong, but the company is an interesting, speculative investment based on an expectation that future earnings will rise at a high enough clip to justify its current (and higher) share price.