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 small-cap oil and gas driller Bronco Drilling (Nasdaq: BRNC) were on fire today, climbing as much as 16% after the company announced fourth-quarter results.

So what: For the quarter, Bronco's revenue leapt 135% from the same quarter last year, while earnings per share -- excluding one-time charges -- came in at $0.06. Revenue of $37.3 million topped the $36.7 million that Wall Street analysts expected, while the adjusted EPS bested an estimated $0.01 loss.

Now what: Fellow onshore driller Union Drilling (Nasdaq: UDRL) also posted positive fourth-quarter results, and its management team had some optimistic comments about what's ahead for 2011. Specifically, they noted that dayrates have started to firm up and that there's a growing demand for oil versus natural gas drilling. The excitement pushed Union's stock up as much as 37%, while other drillers, including Vantage Drilling, also appeared to get a bump from the news.

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