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 auto-supplier LKQ (NASDAQ:LKQ) were looking stronger today, gaining as much as 15% after posting an impressive second-quarter earnings report.

So what: The maker of replacement auto parts and systems delivered an adjusted earnings per share of $0.26, better than expectations of $0.25, and said revenue grew 24% to a record $1.25 billion. That figure was much better than the $1.19 billion analysts had expected. CEO Robert Wagman noted that organic revenue growth was 13.1% for parts and services, while European organic growth surged 37.8%. Management also lifted its guidance saying it now expects revenue grow of 8.5%-10.5% for the full year versus the previously stated 6.5%-8.5% and EPS of $1.03-$1.10, versus $1.00-$1.09.

Now what: Wall Street always like to a bump in guidance so the jump in share price shouldn't be a surprise. However, I'm a little concerned about the sustainability of growth in Europe as new car sales have stalled amid the recession, leading to high demand for replacement parts, so I wouldn't expect to see that level of growth continue for an extended period. With a P/E of 32 and modest growth prospects then, LKQ looks overvalued after today's rise.