Another year of double-digit returns?

With such a choppy start to the New Year, many are left to wonder if the party is over.

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Not so fast, sport fans! Although it appears that the bull market of the past 5 years was beginning to stumble – it does not appear that this bull is dead.

The end of last year saw a marked increase in volatility as some old concerns were made fresh again. Greece and the euro zone, although never really "out of the woods," had seemed to become a bit more stable as the global economy enjoyed a slow, lumbering comeback. That was, until the end of December, when Greek elections threw us a curveball. Threats of pulling out of the euro zone and possibly defaulting on its debt sent the markets into a tizzy.

The lack of a coordinated European Central Bank action and renewed concern over their inability to create change and economic stability only added fuel to the fire. Oil became the talk of the town as it began to tumble in price. Arguments are made on both sides of the demand/supply equation – but the sense is that it is much more a supply issue than a demand issue. The U.S. is now the second largest oil-producing nation and has become an exporter of oil, creating a real challenge to the status quo. OPEC and Saudi Arabia are not happy – increasing production leading to increasing supplies led to decreasing prices, causing turmoil in the energy space. Yet, it caused huge benefits in so many other industry groups. Investment banks had rung the alarm bells that lower oil prices were going to be a disaster for the global economy. We will begin to see what exactly lower prices means beginning this week with earnings announcements.

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Geopolitical tensions continue to simmer, as usual, and remain a source of concern. Lower oil prices have the ability to cause instability across a range of countries – Russia being the one to watch. Pressure applied by OPEC will have a stinging effect on countries like Russia, Venezuela, Iran and even the U.S., so this theme is sure to play out for a while.

So, now the bullish case for the markets in 2015. The U.S. economy remains vibrant, which should, in itself, provide strong support for U.S. stocks. We have ended our formal stimulus plan but now look to play the real-life version of the board game Clue. We must ask ourselves — "What will the Federal Reserve do now?" Will they announce a 0.25-percent rise in April in the Rose Garden? Or will it be 0.5 percent in August at Jackson Hole? No matter, investors are aware that rates are going to rise at some point and the markets are adjusting to the eventual road to normalization.

Earnings season officially kicks off this week and analysts expect earnings to grow in the 8-percent to 10-percent range for all of 2015 – and with the broader market trading at near 16 x these estimates, it may put us at a slight premium to historical averages. But considering the state of other parts of the world, investors do not appear to be that concerned. With an improving U.S. economy, stronger consumer, lower energy prices and a strong dollar, investors could see another year of 10-percent to 12-percent returns on the S&P – taking that index to the 2275 level.

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But will the ride be slow and steady or will it be full of potholes? My sense is that we will see plenty of potholes along the way. And, if January is any guide, then investors should be prepared for a bumpy road – especially as we await the results of this month's ECB meeting and Greek elections.

Looking ahead, investors wonder what the unforeseen black swan event could be that might derail this bull market. Here are a few possibilities:

* Increasing numbers of cyber-terrorist related events. It is exactly what we can't see that has the ability to wreak havoc on financial markets.

* Potential political instability created by weakening oil prices in so many countries that rely on oil revenues to fund the governments.

* Massive debt default by the Russians, which, in turn, would infect financial institutions – mostly in Europe. Any weakening or hit to financial institutions has the ability to create panic once again in global markets causing long-term investors to bail.

These are only some of the concerns that so many are discussing.

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The U.S. economy appears to be the best insulated right now. Any concerns that investors have with other parts of the world may result in investors looking once again to the U.S. for stability and opportunity.

Hold on and strap in. The road ahead is certainly not for the faint of heart – but I suspect that 2015 will be another positive year for investors in the U.S.

Commentary by Kenny Polcari, director of NYSE floor operations at O'Neil Securities. He is also a CNBC contributor, often appearing on "Power Lunch." Follow Kenny on Twitter @kennypolcari and visit him at kennypolcari.com.

Disclosure: The market commentary is the opinion of the author and is based on decades of industry and market experience; however no guarantee is made or implied with respect to these opinions. This commentary is not nor is it intended to be relied upon as authoritative or taken in substitution for the exercise of judgment. The comments noted herein should not be construed as an offer to sell or the solicitation of an offer to buy or sell any financial product, or an official statement or endorsement of O'Neil Securities or its affiliates.