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 engineering and construction firm Shaw Group (NYSE: SHAW) plummeted nearly 20% in intraday trading Monday on fears that its nuclear power plant segment could be in jeopardy in the aftermath of Japan's nuclear meltdown.

So what: Despite a statement from Shaw CEO J.M. Bernard, J.R. that "we do not believe there will be an impact on Shaw's nuclear projects currently under construction in the United States and China," Japan's earthquake-damaged nuclear reactors has Congress and, in turn, Wall Street, seriously questioning America's use of nuclear power going forward. While nuclear power currently represents less than 10% of Shaw's business, a D.A. Davidson analyst downgraded the stock as it represents a huge part of the company's future growth plans.

Now what: I'd look cautiously into this plunge as possible entry point. Although nuclear energy accounts for nearly half of Shaw's backlog, Shaw also reassured investors that "our customers have indicated they intend to move forward, and we believe the construction timelines will continue as planned." With the stock now trading at a clear forward P/E discount to rivals like Fluor (NYSE: FLR) and Jacobs Engineering (NYSE: JEC), Shaw seems like well-priced bet on these nuclear fears eventually blowing over.

Interested in more info on Shaw? Add it to your watchlist.

Fool contributor Brian Pacampara owns no position in any of the companies mentioned. Try any of our Foolish newsletter services free for 30 days.

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