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: Penn Virginia (NYSE: PVA) dropped 10% in intraday trading today, after badly missing earnings expectations and announcing senior management changes.

So what: Investors drilled this oil and gas explorer on news that non-GAAP earnings per share were -$0.51, compared with $0.04 in the year-ago quarter and the consensus estimate of -$0.19. Investors also learned that the replacement for retiring CEO James Dearlove is former COO Baird Whitehead; no COO backfill was named.

Now what: A widening gap between the prices of crude oil and natural gas has Penn Virginia -- along with other companies such as Anadarko (NYSE: APC) and Petrohawk (NYSE: HK) -- investing heavily in natural gas liquid exploration. Penn Virginia's investments are outpacing related revenue, however, at least partially because of "exploratory setbacks." Management said it does not expect production levels to improve until the second half of 2011.

Interested in more info on Penn Virginia? Add it to My Watchlist.

Fool contributor Cindy Johnson owns no shares of any company named above. We Fools don't 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.