The world, of course, is full of them.

Europe, as Bhansali pointed out, is still coming out of its own economic crisis and is likely to see additional debt restructurings such as Greece's. Japan's demographics are troubling, given its aging population and the likelihood of conflicts with China. Emerging economies, meanwhile, had been a sweet spot but are experiencing a slowdown.

In the United States, uncertainty over monetary policy remains high, given the coming departure of Ben Bernanke as head of the Federal Reserve. Debt-ceiling negotiations – or non-negotiations – in Congress aren't helping. Also, corporate profitability is slowing and while housing has been a bright spot, that market is feeling the effect of rising rates.  

So, how should advisors position their clients' portfolios for retirement amid all of this turmoil?

A "more robust" portfolio in today's environment, Bhansali said, includes emerging market securities, real estate commodities and inflation-linked bonds. Buying put options is also a popular form of tail risk hedging.

The problem with puts, however, is that despite demand, fewer and fewer in the market are willing or able to sell these options. Banks, for example, are selling fewer long-dated options as they respond to regulatory pressures to cut their own risks.

That's made such hedges more expensive, critics say. Pimco acknowledges that point but notes the cost of hedging in absolute terms is back to pre-crisis lows.  

In any case, Bhansali's point about doing more to manage risk is hard to ignore. And so Pimco's asset allocation strategy has now been distilled thusly:

• Optimal allocation to risky assets becomes more defensive.
• Cash becomes more valuable.
• Downside risk dominates asset allocation decisions.

Buying and holding equities alone won't work, Bhansali said, and certainly not over the long term.

"Don't abandon everything you've got," he told the audience. "All we're saying is don't leave retirement to the throw of the dice."