“The massive volatility and sharp equity-price correction hitting global financial markets signal that the most advanced economies are on the brink of a double-dip recession,” Roubini writes.

The second: A no less enlightened bearish overview comes from money manager Jeremy Grantham, chairman of GMO LLC, who has been sour for years on global economic prospects.

Grantham’s recent missive “Danger Children at Play” rambles on about the end of the U.S. empire, yet cobbled together some cogent ideas on how to regard our fin de siecle.

The third: cold-porridge taste comes from bond manager Jeffrey Gundlach of DoubleLine Capital LP, the most pessimistic of the three. Gundlach likens the current environment to the blow-up of 2008.

Gundlach told Advisor One “the time is ripe” for another AIG or Lehman-level collapse “based upon the growing lack of confidence in the growing debt of Spain, Italy, Greece, Portugal, Ireland and ultimately of France.”

Like the other bears, Gundlach is not keen on the stock market or the ability of politicians or central banks to pull us out of this muck and mire.

So how to handle the 3 'bears' in one's retirement investments (such as 401k investments, IRAs, taxable accounts) portfolio? Here are three ways:

• For Roubini's 'equity-price correction', tactical asset allocation is one way to follow macro events in the world to properly adjust risk exposure in your portfolio. Cautious and proper risk management is the key to success in long term investment.
• For Jeremy Grantham's rambling on Washington's politics and our long term structural problems, diversification and high quality stocks are the first line of defense. Portfolio diversification means investing in a wide array of assets while emphasizing on high quality companies' stocks for equity portion exposure. See our SeekingAlpha article 10 High Quality U.S. Stocks From GMO (GMO Quality IV (GQEFX))
• For Gundlach's emphasis on treasury bonds and notes (see SmartMoneyIQ Managers for DoubleLine Total Return Bond (DBLTX) asset exposure), one should adopt a nimble way to have some exposure in treasury bonds (TLT) as a way of hedgeing.  Portfolios in Permanent Global Portfolio ETF Plan or David Swensen Six ETF Asset Individual Investor Plan have treasury bonds as candidate funds for asset allocation strategies.

Ultimately, no body knows for sure whether bears or bulls will prevail in the coming months or years. A diversified portfolio with sound risk management practice is the best way to 'beat out' the bears in one's retirement investments.

Symbols: SPX, TLT, SPY, EFA, EEM, IYR, DBC, AGG, DBLTX, GQEFX, Retirement Investments, 401K Investments, Risk Managment