The beginning of a double-dip? The U.S. markets are tanking this morning on fears of a default in Greece and a bank crisis in Europe at large. Currently the Dow Jones Industrial Average is down more than 200 points, and the S&P is down nearly 2 percent, making for a 15-month low for world stocks. If you're feeling somewhat superstitious/pessimistic this morning, you may not want to look at a chart circulated by a Citigroup technical analyst, and passed along by Business Insider's Joe Wiesenthal, titled "For Those Who Don't Believe History Repeats Itself..." noting that the S&P closed at precisely the same level yesterday as it did on October 3, 2008—one day before the markets took an absolute killing:

Scary stuff! For more grounded contextual analysis, The New York Times's Joshua Brustein explains what's happening in Europe that's frightening investors.

Early Tuesday, finance ministers from the 17-nation euro zone postponed moves to release the next installment of aid to Greece, which means that Greece is now unlikely to receive 8 billion euros ($10.6 billion) before November.

European banking shares fell sharply, led by Dexia, whose value has plunged this week because of its exposure to Greek debt...

“What you’re now beginning to see is they [investors] are now picking out the banks. Dexia is the weakest,” Justin Urquhart Stewart, director at Seven Investment Management, told Reuters.

"Politicians have to stand behind these banks — whether you call it state support, nationalization, you have to keep the financial system working otherwise we will end up with another credit crisis."