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 oil drilling equipment maker Robbins & Myers (NYSE: RBN) surged 27% today after larger rival National Oilwell Varco (NYSE: NOV) offered to acquire it for about $2.5 billion.

So what: The all-cash deal -- National Oilwell's largest since its purchase of Grant Prideco in 2008 --values Robbins & Myers at $60 per share and represents a 28% premium to its closing price on Wednesday. The acquisition is just the latest of several in the sector as companies look to cash in on the drilling boom, and judging by National Oilwell's small percentage gain, Wall Street seems fine with the purchase price.

Now what: Analysts estimate that the deal will add about $0.25-$0.35 to National Oilwell's EPS in 2013. "I am particularly enthusiastic about the prospect of incorporating their downhole tools, pumps and valves into National Oilwell Varco Petroleum Services & Supplies and Distribution & Transmission segments," National Oilwell Chairman and CEO Pete Miller said. "We feel that our combined manufacturing infrastructure and portfolios of technology will further advance our presence in the oil and gas markets we serve." So while Robbins & Myers shares are likely all popped out, National Oilwell is still certainly worth looking into.

Fool contributor Brian Pacampara owns no position in any of the companies mentioned. The Motley Fool owns shares of National Oilwell. Motley Fool newsletter services have recommended buying shares of National Oilwell. Try any of our Foolish newsletter services free for 30 days.

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