Investors were hoping 2016 would be a fresh start after the US stock market sputtered to wrap up 2015. Instead, what they got was rotten.

Major averages kicked off the year with their worst week in more than four years as investors fled the market, and fear is on the rise that a full-blown bear market may be lurking. While that may be overstated, markets do face an unsightly assortment of obstacles.

The volatility surrounding the world's second largest economy is a primary concern of investors. Attempts by officials there to tamp the selling in equities and the steady devaluation of the yuan have fed worries about capital flight. Moreover, a weakening in the currency could hurt demand for imports, particularly those sold in dollars like oil.

US exposure to China in terms of gross domestic product (GDP) is minimal - only about 0.7 percent of overall GDP, according to Citigroup strategists - but the knock-on effect for other emerging economies cannot be ignored. Furthermore, Citigroup notes that companies with more than 20 percent of revenues from China, including Apple, Texas Instruments and 30 others, have performed worse than the overall market since mid-2015.

Even though the US economy is continuing to grow as evidenced by recent figures on auto sales and jobs growth, albeit at a slowing pace, public company earnings are in recession. Estimates have fallen sharply in recent days, with fourth-quarter results expected to fall by 4.2 percent from the year-earlier period from a 3.7 percent drop anticipated at the beginning of 2016.

The forward price-to-earnings ratio, as a result of the market's rapid drop in the last week, has retreated to a more historically average 15.3 level, but stocks often need to become cheaper to entice investors while markets are in a swoon like this. Should profit estimates continue to fall, that will put more pressure on stock price to decline as well.

Strategists interviewed late Friday noted that the Fed's intentions to keep raising rates at a steady clip will continue to drive volatility as yields in the US rise and credit conditions tighten.