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 coal miner Arch Coal (NYSE:ACI) jumped 10% today, after reporting earnings.

So what: Revenue fell 9% in the third quarter, to $1.09 million, but was ahead of estimates of $1.01. The company also reported a surprise profit of $45.8 million, or $0.22 per share, when analysts expected a $0.16 loss. 

Now what: This could be a sign that coal stocks are starting to bottom because of fundamental improvement. Prices are starting to stabilize, and even rise slightly, and demand is expected to improve. I don't think this is a reason to buy coal stocks due to long-term challenges in the industry, but I'm not as negative on the industry as I was earlier this year given how far they've fallen.

Interested in more info on Arch Coal? Add it to your watchlist by clicking here.

Fool contributor Travis Hoium has no positions in the stocks mentioned above. You can follow Travis on Twitter at @FlushDrawFool, check out his personal stock holdings or follow his CAPS picks at TMFFlushDraw.The Motley Fool has no positions in the stocks mentioned above. Try any of our Foolish newsletter services free for 30 days. We Fools may not all hold the same opinions, but we all believe that considering a diverse range of insights makes us better investors. The Motley Fool has a disclosure policy.