The Dow Jones Industrial Average (INDEX: ^DJI) plunged more than 200 points today, for a whopping 1.6% loss, by far its biggest in 2012.

Greece is once again in the news amid concerns that not enough investors will go along with a March 20 bond swap that is needed for the country to meet the amount it owes. If not enough investors agree to participate, Greece could force a majority-wins vote, but that could trigger credit-default-swap payments and rattle financial markets.

Cyclical materials and construction stocks Alcoa (NYSE: AA) and Caterpillar (NYSE: CAT) took the brunt of the market selloff, for a repeat performance as the two worst-performing Dow stocks. The ongoing crisis in Greece, with its potential to spill over into Europe if not properly handled, may be the most prominent threat to the global economy, but two others have been rearing their heads lately. Yesterday, China's premier reduced its GDP target from 8% to 7.5%; and the potential showdown with Iran has elevated oil prices, temporarily taking the wind out of construction and manufacturing.

Naturally, bank stocks took it on the chin, too. The big five banks, Citigroup (NYSE: C), Goldman Sachs, Morgan Stanley, Bank of America (NYSE: BAC) and JPMorgan Chase, reportedly have a combined $80 billion in exposure to troubled European debt, though they're relying on credit default swaps to hedge that exposure down to $50 billion. Trading has been one of the weakest areas in banking lately, and an exacerbated financial crisis won't help matters one whit.

Hopefully, none of these risks to the economy will materialize, but if things continue down this path we may see cheaper stocks and another buying opportunity. If you're interested in one stock that our chief investment officer picked to crush the market, check out our brand-new report, "The Motley Fool's Top Stock for 2012." It highlights a company that is revolutionizing commerce in Latin America. For a limited time, you can get instant access to the name of this company for free by clicking here.