Sell in May? Nah. Stay for the summer!

"Sell in May and go away," that old Wall Street adage, warns investors to sell their stocks in May to avoid the typical summer decline. I never really understood it — investors typically build portfolios over time, taking advantage of both the strengths and the weaknesses of the stock market. But here we are again. So what do you do?

Well, if we have learned anything over the past 7 years — staying invested is the answer. And why? Because fighting the Federal Reserve is not a wise strategy. And now that we have global central banks joining in the party — it should only encourage investors to keep plowing money into the market.

Beach scene
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Yes, the first quarter was a disaster — macro data in the U.S. was miserable — but the market is trading near all-time highs. Earnings this quarter disappointed almost on a daily basis — but investors did not seem to care. Earnings are history because they're over – it is the forward guidance that is important. European and Asian macro data have also not been a WOW, yet those markets keep climbing. What is the common theme? The central banks. If central banks keep playing such a key role, the markets can never really trade on their own. "Sell in May and go away" makes zero sense.

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What's more, central banks aren't going away. The Federal Reserve is not in any rush to raise rates. June is off the table and my bet is that September is as well. The European Central Bank isn't going anywhere and anytime Chinese or Japanese macro data shows any weakness, the conversation turns to more stimulus and off we go!

I expect the economic data to improve, much like in 2014, when we had a horrible first quarter, only to hit it out of the park by the fourth quarter. 2015 began the same way — and now all the talk is about a "blowout" second quarter. Those results are due in June – just when you would be "away" if you stayed true to the adage. Analysts are raving about the "encouraging" signs about the labor market as initial jobless claims last week fell to 262,000, the lowest reading in 15 years, as wages supposedly rose by 2.6 percent. This Friday brings us the nonfarm payrolls report and all expectations are for a significant rebound, making the April figure the outlier. Talk of better days ahead for the second half of the year is all the rage.

Earnings guidance, for the most part, wasn't horrible. The strong dollar wasn't the disaster that many made it out to be, and oil and energy are on the rebound – which is a bullish sign for the overall health of the economy. The dollar has backed off, offering some solace to the big multinationals, and M&A activity continues at breakneck speed. These are all positive signs and should continue to come together as we move through the summer. Remember: Even as the summer doldrums kick in, the market can quietly tick higher as it digests the improving macro data.

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But, you say, "If the macro data improves, then the Federal Reserve will be forced to raise rates and that will cause the market to suffer." Look, any increase in rates — when it happens — will be gradual and very specific. Investors (and the market) know this — the angst comes when investors (and the market) don't believe the data. This is about to change, I think, and quite honestly, I think it would be welcomed by both investors and the market as it would signal a real return to normalcy. Investors and the market want clarity and normalcy and a program like this should create an environment that allows the Federal Reserve to remain flexible as growth improves. And that, my friends, is good for equities and is exactly the reason why you should not stay away in May.

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.

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