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 Western Refining (NYSE: WNR) fell 10% today as high oil prices put pressure on oil refiners.

So what: The whole refining sector is taking it on the chin today, with Tesoro (NYSE: TSO) and Valero Energy (NYSE: VLO) falling along with Western Refining. As oil prices rise, investors are concerned it will put pressure on margins. Refiners rely on the difference between oil prices and refined products like gasoline for profits.

Now what: The spread between oil price and gasoline, known as the "crack spread," has stayed relatively level today, so the sell-off seems to be a bit overdone. I'm not saying there aren't plenty of reasons to be worried about refiners going forward, but the move today looks to be a panic that should have happened a few days ago. Investors need to keep a close eye on oil prices and the crack spread to see if the economy can handle higher fuel prices. If it can't, refiners could be in for a big correction after a nice ride higher for most of the past year.

Interested in more info on Western Refining? Add it to your watchlist.

Fool contributor Travis Hoium does not have a position in any company mentioned. You can follow Travis on Twitter at @FlushDrawFool, check out his personal stock holdings or follow his CAPS picks at TMFFlushDraw.

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