Sorry David but that makes no sense. Why aren't US companies with large exposure to Europe falling +10% too? Groupon's exposure to European countries going through the debt crisis is negligible. It's only Groupon
While there isn't enough trading history to say with confidence, I don't think it's unreasonable to say that GRPN has a pretty high beta to the broader market, so I would expect it to rise (or fall) several times the % of (most of) the rest of the market.