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: Ameristar Casinos (Nasdaq: ASCA) saw its shares fall as low as 11% in intraday trading Tuesday after announcing that it is no longer considering a potential sale of the company.

So what: For quite some time, the embattled Ameristar has been looking for ways to unlock shareholder value in the face of declining gaming revenues, mounting losses, and a massive debt load. Ameristar shares have performed nicely since the summer -- when it confirmed that one of those "strategic alternatives" included a possible sale -- so it's no surprise that investors are sending the stock down on today's news.

Now what: With Ameristar's "For Sale" sign coming down, it's tough to see another powerful catalyst for the shares. It looks as if Ameristar will just stick to its existing business plan, but a brutal economy, coupled with intensifying pressure from regional players like Pinnacle Entertainment (NYSE: PNK), make the stock an easy fold for conservative Fools. If you really must play in the casinos, operators with huge Asian exposure like Melco Crown (Nasdaq: MPEL), Las Vegas Sands (NYSE: LVS), and Wynn Resorts (Nasdaq: WYNN) seem like your best bets.    

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Fool contributor Brian Pacampara owns no position in any of the companies mentioned. Ameristar is a Motley Fool Hidden Gems selection. Melco is a choice of Global Gains. Try any of our Foolish newsletter services free for 30 days. We Fools may not all hold the same opinions, but we all believe that considering a diverse range of insights makes us better investors. The Fool's disclosure policy always gets a perfect score.