The financial markets can be weird.

In a relatively short time, we've seen traders push natural gas futures to a record level of more than $15.50 per million British thermal units (MMBtu) and then chop it down to less than $7.30. And there's also plenty of weirdness among energy equities, considering that stocks like Apache (NYSE:APA) and Anadarko (NYSE:APC) don't seem to get quite an equal shake when compared with the stocks of some of their large independent brethren.

And it's not as though Anadarko had a bad quarter to cap the year. Revenue rose about 39%, even though the company experienced lower production relative to the year-ago period, mostly because of asset sales. Not only was revenue growth on the strong side, but operating income also jumped a nice 87% as the company continues to stay ahead of rising production costs.

Looking at some of the other numbers relevant to a large oil and gas concern, we see that proven reserves grew by 6% for the full year and that Anadarko achieved a robust 180% reserve replacement ratio. While that stat is helped by the lower reported production for the year, it's still not a bad overall result.

What's not quite as good is that the company modestly trimmed guidance for 2006 production growth to something on the order of 4%-8%. Still, Anadarko continues to report good drilling success and will be ramping up deepwater Gulf of Mexico assets in 2006.

As we've seen in the past few months, the energy markets are volatile and prone to overshooting both high and low. Back in December, energy traders acted as though we were heading into a new ice age, while today, some seem to believe the energy boom is over. That certainly makes investing in this sector trickier, and I'd argue that it makes stock selection even more important.

I'm not sure I'd want to own just any energy stock these days. Anadarko isn't a bad pick at all, but I'd still probably focus more of my attention on the likes of Apache or maybe operators like Occidental (NYSE:OXY) and Canadian NaturalResources (NYSE:CNQ).

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Fool contributor Stephen Simpson has no financial interest in any stocks mentioned (that means he's neither long nor short the shares).