hzhan1, the refinery stocks in general have been hit hard recently, not just WNR.
If you look at the 'interactive price' chart on yahoo for VLO, or TSO or WNR, they all show a 7.5% to 8.25% price drop if you choose the 1 month time window.
As to why the refiners have been hit, I'm not sure, but I know that VLO was given at least one 'downgrade' recently, maybe there were others as well.
In my experience, analysts tend to give downgrades AFTER price has been crushed, and then give upgrades about the time that price is getting overbought and perhaps is close to peaking-out, so it sort of amazes me that downgrades/upgrades move stock prices as much as they do.
But the fact is that for whatever reason, those upgrades/downgrades do seem to move stock prices, at least for a short while after they are issued.
VLO reported great earnings recently so they are a known quantity in that respect. The market is waiting for WNR's earnings, so in the current climate of market fear, money may be moving towards VLO because it seems like more of a 'sure thing'.. I would expect if WNR's earnings are okay that we'd start bouncing back up..