These are the days traders live for

OK, so now it's over. Mario Draghi and the European Central Bank executed on the famous "Whatever it takes" quote. Draghi announced a monthly 60 billion euro ($70 billion) quantitative-easing program to run through September 2016 - slightly more than what the market was expecting.

European Central Bank President Mario Draghi addresses an ECB news conference in Frankfurt January 22, 2015.
Kai Pfaffenbach | Reuters
European Central Bank President Mario Draghi addresses an ECB news conference in Frankfurt January 22, 2015.

European markets continued to surge as the announcement offered up some relief and much needed clarity on the future of the euro zone. It also allayed any fears that this multi-nation union is not laser-focused on a broad recovery. U.S. stocks initially moved higher but remain volatile. Up in early trade only to go negative very soon after the opening only to reverse again and test resistance at the 50-day moving average.

Read MoreOpen-ended European QE starts 'with a bang'

So now it begs the question: Does this change the strategy in Europe? Well, from a long-term perspective, not so much. What it does do, though, is offer investors the chance to once again focus on the broader macro fundamentals. It also offers up a chance for individual countries to enact real structural reforms while the ECB is willing to support them in this transition. For global investors, this is good news but the results will take months to come to fruition. The thoughtful, steady approach is always the key.

Does this change strategy in the U.S.? No. It only solidifies the commitment of the Europeans to address the problem — and this is good for the global economy as well as the U.S. economy. And if you believe that the U.S. economy is strong, this only further supports continued investment in U.S. stocks.

Read MoreECB needs to buy more bonds than Fed: CIO

For the trader, well, that's a different story. The volatility that this move created and will continue to create will cause dramatic moves across a range of assets providing opportunities to trade.

The key on days like this is to be vigilant because the tone of the market can change on a dime if new analysis or sense of understanding offers up the idea of an unforeseen outcome. We already saw this early today: The S&P has had a 38-point range -- up 12 points, then down 26, then up 20 -- all within the first hour of trading. The key as a trader is to not get married to any one position. We have all seen how the recent volatility has caught so many on the wrong side of a trade if you remain stubborn. Agility, quick thinking and the ability to shift gears on a moment's notice will continue to reward the active/aggressive trader.

These are the days the trader lives for.

Read MoreLive blog: Markets cheer European QE

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

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.