4 Black Swans That Could Jolt the Market in 2013

The issue of Iran's nuclear ambitions has been in the news for so long, that investors seem to have forgotten about it. Although the U.S.-led sanctions are having a major effect on the Iranian economy, there has been little movement by the Iranian government to seek a face-saving compromise.

Iran will be voting for a new president this summer, as Mahmoud Ahmadinejad's term expires in August. If his successor is a hand-picked choice of the Ayatollah Khamenei, then global strategists may well conclude that Iran will maintain or deepen its hard line stance. And looming military tensions between Iran and the West would trigger the possibility of a closure of the Strait of Hormuz, which is the only open sea passage from the Persian Gulf to the ocean. In such a scenario, oil prices would quickly spike much higher, dealing a major headwind to the global economy -- and stock markets.

Chairman Ben Bernanke has wisely sought to calm the markets by repeatedly stressing that the Fed won't start raising rates until the U.S. economy shows greater vibrancy. Although the bank is unlikely to start raising rates in 2013, the official statements released after Fed meetings could start to shift in tone. The current language of perpetual monetary accommodation could eventually be replaced by language that hints of groundwork for eventual tightening. And once investors start to see a shift coming into focus, they may lose their appetite for equities. In some -- but not all -- instances when the Fed has moved to boost interest rates, the stock market has weakened.

In addition to this tightening scenario, there is always the possibility that existing Fed policy starts to lose its effectiveness. The Fed's various Quantitative Easing (QE) measures have generally helped the bond and stock markets, but the Fed's balance sheet is now so stressed, that we simply don't know how the market will respond to any interest rate hiccups as the effects of the various QE programs start to wane.

The ticking time bomb has been unplugged for now, as House Republicans voted to extend their timeframe for another government shutdown deadline into the spring. The decision to defer a showdown is ostensibly to buy more time to come to a bipartisan agreement on a path to close the still-massive government budget deficit. But the two sides remain so far apart (and have identified few areas for compromise) that a far-reaching agreement that keeps our government debt from eventually hitting $20 trillion seems increasingly unlikely.

Even as the total amount of government spending has grown quickly in each of the past four years, the market has moved higher and higher. So investors have already concluded that the rising level of government debt simply has no bearing on the markets. Yet you can only stretch a rubber band so far, and as long as inaction reigns, the debt load swells higher, and the eventual moves to start paying down our debt will have a much more draconian effect on U.S. economic growth. It's a notion that has been seemingly ignored until this point, but could be the "Black Swan of 2013."

China's hefty ownership of U.S. bonds has been remarkably positive to our economy, helping to keep interest rates down and enabling us to keep issuing more debt without any real ramifications. 

Yet China's new leadership has given clear signs of shifting its economy in the direction of domestic consumption. If they're serious about stimulating domestic demand, then they would have less incentive to pursue a cheap currency policy.

As we saw with Japan in past decades, a weak currency only makes sense in the context of an export-led economy. Chinese policy makers also worry about inflation, and one way to keep price pressures at bay is to let your currency strengthen (which weakens import prices).

Lastly, China surely has an eye on the U.S. budget mess, and may eventually follow through on its threat to strongly decrease its ownership of U.S. bonds. Without China, Uncle Sam would be paying much higher interest rates.