The Model S is claimed to be the safest sedan in production right now. I don't think it is unnatural for people to scrutinize these fires, especially since the source of the fire is potentially different from gasoline-based vehicles.

Of course, the investor types will sensationalize it all, but I suspect most people are just curious on what the overall statistics will converge to. Are fires more or less likely in Tesla vehicles compared to gasoline vehicles? We don't have enough data to say yet. When a fire does happen, is it more dangerous or less in a Tesla compared to a gasoline vehicle? Again, probably not enough data, but the odds are looking good so far.

Finally, a volatile stock price is to be expected when there's so much speculative trading going on surrounding the company.