NEW YORK ( TheStreet) -- So April turned out to be at least uncooperative, if not cruel, and now May is upon us. Should investors head for the exits or skip summer vacation this year?

Sam Stovall, chief equity strategist at S&P Capital IQ, tackled this question on Monday, noting the performance data does seem to back up the "sell in May" part of the old trading adage.

"Over the past 67 years, the S&P 500's performance in May has been a bit lackluster, recording an average advance of only 0.31% vs. the average gain of 0.67% for all months, thereby ranking it eighth," Stovall wrote. "The frequency of a monthly advance has also been slightly sub-par at 57% versus the average 59%."

The track record over the past two years is what's freshest in investor minds, though, and those results are even worse, especially for 2011, when the S&P 500 peaked above 1370 during the fifth month then finished the year at 1257.60, down 8.2% from the high and ultimately flat for the year.

That's created something of a "fool me once, shame on you, fool me three times, shame on me" mentality, Stovall quipped while still acknowledging the historical argument is fairly compelling.

"Since 1945, the S&P posted its strongest six-month average return from November 1 through April 30, recording an advance of 6.8% (excluding dividends), versus an average gain of 4.1% for all 12 rolling six-month periods," he said.

The S&P 500 has posted gains 78% of the time for all November-April periods in that time vs. 67% for all other six-month periods. Conversely, for the May-October period, the index has gained just 1.2%, the worst of all rolling six-month periods, according to S&P Capital IQ.

As for 2012, given the decline in April, Stovall said the usual exodus out of stocks could be pushed back a bit and investors should consider rotating into defensive sectors like consumer staples and health care, which have outperformed the broad market in the summer months over the past two decades.

He also noted that the average 1.2% gain in the May-October period referenced earlier is "still better than what an investor would receive from a money market fund" and that there are tax ramifications and transaction costs for investors to consider. The firm's year-end target for the S&P 500 sits at 1450, implying potential upside of 3.7% from Monday's close at 1398.

" T hough a pullback in prices can't be ruled out, and 'Sell in May' may only be delayed until the 'Swoon in June,' history reminds us (but does not guarantee) that there is little historical evidence encouraging us to sell out of stocks altogether," Stovall said. " E specially when an investor could have added 400 basis points per year by rotating out of the S&P 500 and into the S&P 500 Consumer Staples and Health Care sectors from M-O May to October ."

As for tomorrow's scheduled news, Tuesday's most high-profile reports are from Dow component Pfizer ( PFE) and Sirius XM Radio ( SIRI), whose sub-$5 per share price makes it a day trader's delight.

Pfizer shares are up 10% in the past year, but roughly flat so far in 2012. The drug maker is fresh off last week's agreement to divest its Nutrition business through a sale to Nestlé for $11.85 billion. The company is expected to report earnings of 56 cents a share in the first quarter on revenue of $15.47 billion, and it will be providing updated guidance to reflect the divestiture, which is expected to be completed in the first half of 2013.

Meantime, with a year-to-date gain of nearly 25%, Sirius XM has been a solid outperformer in 2012. The average estimate of analysts polled by Thomson Reuters is for the satellite radio company to deliver a profit of 2 cents a share on revenue of $803.8 million in the first quarter. An in-line revenue performance would translate to year-over-year growth of 11%.

Sirius watchers will be combing through the subscriber count and churn rate to get a sense of how well the price increase the company announced back in September has been received. A major topic on the conference call will be management's expectations of any fallout from the recent legal scuffle the company won against shock jock Howard Stern.

The sell side is very bullish ahead of the report with 10 of the 14 analysts covering the stock at either strong buy (4) or buy (6) and the 12-month median price target sitting at $2.55. Sirius, which is always heavily traded with the stock's trailing three-month daily average churn at 52 million, finished 2011 with 21.9 million subscribers and has forecast ending 2012 at 23.2 million.

Check out TheStreet's quote page for Sirius for year-to-date share performance, analyst ratings, earnings estimates and much more.

Morning reports are due from Arch Coal ( ACI), Archer-Daniels-Midland ( ADM), Avon Products ( AVP), Automatic Data Processing ( ADP), Becton, Dickinson & Co. ( BDX), Biogen Idec ( BIIB), BP plc ( BP), Bruker Corp. ( BRKR), Corn Products ( CPO), Cummins ( CMI), DineEquity ( DIN), Domino's Pizza ( DPZ), Ecolab ( ECL), Fresh Del Monte Produce ( FDP), Genesee & Wyoming ( GWR), Harris Corp. ( HRS), Hospira ( HSP), Kulicke & Soffa Industries ( KLIC), Legg Mason ( LM), LendingTree ( TREE), LoJack ( LOJN), Marsh & Mclennan ( MMC), Martin Marietta Materials ( MLM), Office Depot ( ODP), P.F. Chang's China Bistro ( PFCB), Radian Group ( RDN), Spirit Airlines ( SAVE), Thomson Reuters ( TRI), TRW Automotive ( TRW), Valero Energy ( VLO), and ViroPharma ( VPHM).

The late roster features Amdocs ( DOX), Bankrate ( RATE), Broadcom ( BRCM), Career Education ( CECO), CBS Corp. ( CBS), Chesapeake Energy ( CHK), Consolidated Graphics ( CGX), Fiserv ( FISV), General Growth Properties ( GGP), Genworth Financial ( GNW), Jazz Pharmaceuticals ( JAZZ), John B. Sanfilippo & Sons ( JBSS), Kforce ( KFRC), Kindred Healthcare ( KND), Nutrisystem ( NTRI), Papa John's International ( PZZA), Peet's Coffee & Tea ( PEET), Plantronics ( PLT), Sturm Ruger & Co.TICKER TYPE="EQUITY" SYMBOL="RGR"/>, True Religion Apparel ( TRLG), UnumProvident ( UNM), and WebMD ( WBMD).

Tuesday's economic calendar features the Institute of Supply Management's manufacturing index for April at 10 a.m. ET with the consensus calling for a slight decline to 53, according to; construction spending for March at 10 a.m. ET, estimated at a 0.5% increase; and auto and truck sales for April due in the afternoon.

-- Written by Michael Baron in New York.

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