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: Manitowoc (MTW 0.48%) shares lost control today, tanking 6% in trade as a disappointing manufacturing report from China weighed heavily on the crane maker's prospects of making it big in the important market. In fact, the bearishness spread across the board, with shares of peers Terex (TEX 1.29%) and Caterpillar (CAT 1.82%) also losing 6% and 3%, respectively in today's trade.

So what: The Chinese Purchasing Managers' Index shrank for the first time in six months in December, even breaching the crucial 50 mark to hit 49.6. That indicates the manufacturing sector is contracting, which bodes ill for Manitowoc. China is a considered a key growth market and an investment hot-spot for construction-equipment companies, so any headwind in the market could be an impediment to growth.

For Manitowoc, in particular, trouble from China started brewing much before this manufacturing report was released. Just earlier this week, Manitowoc sold off 50% of its stake in a joint venture set up in 2008 with a Chinese company to manufacture mobile hydraulic cranes. Manitowoc expects to record a loss of about $36 million from the transaction, which should be reflected in the company's upcoming fourth-quarter numbers.

In September 2013, Manitowoc also exited its joint venture with China-based Shantui Investment which was created only in January last year. Among other reasons, Shantui cited  a "sharp decline in the construction machinery market in China" and government delays in project approvals for calling off the agreement. Manitowoc had bet on Shantui's solid foothold, strong dealer network, and brand name in China to increase presence in the mobile crane market. Unfortunately, Manitowoc has little to boast of in China now.

Now what: You may be wondering, then, that if Manitowoc is hardly present in China now, why should a dour economic report from the nation hit the shares so hard?

I can see two reasons behind that. One, Manitowoc still has its tower crane operations in China, and even plans to build upon it. So it's not completely insulated from headwinds in the nation. Two, and more importantly, a meltdown in China is bound to have ripple effects on other Asian and emerging markets. Manitowoc derived nearly 10% revenue from Asia alone in 2012, so that isn't good news for the company.

That said, Manitowoc may still be better off than peers, since it gets a greater chunk of sales (more than 50%) from North America. Comparatively, both Caterpillar and Terex generate nearly 70% revenue each from markets outside the U.S. This has actually helped Manitowoc deliver better numbers than peers for some quarters, and I don't see a reason why it shouldn't continue to do so. Morgan Stanley even upgraded the stock earlier this month on the back of improving construction activity in the U.S.

If there's anything that could slow Manitowoc down this year, it's a slow food service equipment business and weak financials. But no company is perfect, so Manitowoc's drop today may even be considered an opportunity for long-term investors.