Is this a bubble market? Here's one way to tell

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Market's in bubble territory when ...

Major market averages may not have much further to fall before indicating that something considerably worse is in store.

Technical analysis is putting key stock indicators near what Walter Zimmerman, chief market technician at United-ICAP, calls the "must-hold" levels—areas that have not been violated since the March 2009 lows that kicked off the heretofore powerful bull market run.

For the S&P 500, that line in the sand happens at the 1,785 level—just about 2 percent from trading levels at midday Tuesday.

For the Nasdaq, which is receiving more attention since it has suffered the steeper declines and is near a correction drop of 10 percent, the level is around 3,830—about 3.5 percent from the current mark.

Break those points, and Zimmerman warns that a highly uncomfortable time lies ahead for bullish investors.