Both reports will give investors a better idea about the strength of the economy and what's next for the Federal Reserve's stimulus program. Investors will hear from the Fed on Wednesday after the central bank winds up a two-day policy meeting. The Fed's stimulus has been a major factor supporting a four-year rally in stocks.
The Standard & Poor's 500 index dropped 6.32 points, or 0.4 percent, to 1,685.33.
Seven of the 10 sectors in the index fell. The declines were led by energy companies and banks.
The benchmark index is still up 4.9 percent in July, and the S&P 500 is on track to have its best month since January. The index jumped this month, climbing to an all-time high July 22, after Fed Chairman Ben Bernanke assured investors that the Fed wouldn't cut its stimulus before the economy was ready. The central bank is buying $85 billion a month to help keep interest rates low and encourage borrowing and hiring.
Stocks may struggle to add to their gains, given that expectations for the economy remain modest, said Scott Wren, a senior equity strategist at Wells Fargo Advisors.
The U.S. economy is forecast to have grown just 0.5 percent in the second quarter, according to data provider FactSet. That would be slower than the 1.8 percent annual rate the economy expanded at in the first three months of the year.
"I don't think you're going to see the market sustain much higher levels than this," said Wren. "All this data is going to show that we are slowly improving, but it's a slow process and there's not much to get excited about."
A trio of corporate deals caught investors' attention Monday but failed to ignite the broader market.
Saks jumped after Canadian retailer Hudson's Bay, the parent company of Lord & Taylor, agreed to buy the luxury store operator for $2.4 billion, or $16 a share. Saks rose 64 cents, or 4.2 percent, to $15.95.
Interpublic Group, a big advertising company, gained after Omnicom Group, another big advertiser, agreed to combine with France's Publicis Groupe to create the world's largest advertising company. Interpublic rose 74 cents, or 4.7 percent, to $16.61.
The stock closed higher even after Interpublic CEO Michael Roth said that he saw no need for a major merger to keep the company moving forward.
Omnicom jumped in early trading, climbing as high as $70.50, but ended the day down 45 cents, or 0.6 percent, at $64.75.
Perrigo also featured in the mergers and acquisitions news. The drugmaker agreed to buy Ireland's Elan for $8.6 billion. Perrigo fell $9.06, or 6.7 percent, to $125.17.
The deals should be positive for the stock market in the long run, and should be followed by more merger activity, said Dan Veru, chief investment officer at Palisade Capital Management. Companies are sitting on record cash balances and borrowing costs, though rising, are still close to record lows.
"Companies are struggling to grow organically," said Veru. "So, how do they grow? They grow by buying other businesses."
The Dow Jones industrial average fell 36.86 points, or 0.2 percent, to 15,521.97. The Nasdaq composite dropped 14.02 points, or 0.4 percent, to 3,599.14.
Investors will also be focusing on corporate earnings this week.
Just over half of the companies in the S&P 500 index have reported earnings for the second quarter. Analysts are currently forecasting earnings growth of 4 percent for the April-through-June period, according to S&P Capital IQ. That's the slowest rate of growth in three quarters.
In government bond trading, the yield on the 10-year Treasury note rose to 2.59 percent from 2.56 percent Friday. The note's yield, which moves inversely to its price, has climbed almost 1 percentage point since the start of May, when it hit its low point of the year, 1.63 percent.
Higher government bond rates push up mortgage rates, which could threaten the housing recovery.
The number of Americans who signed contracts to buy homes dipped in June from a six-year high in May, the National Association of Realtors said Monday. The slight decline suggests higher mortgage rates may be starting to slow sales.
Should rates rise too quickly the Fed will likely keep up with its stimulus for longer, said Colleen Supran, a principle at Bingham, Osborn and Scarborough, a wealth management firm.
"We really need the housing market to stay on track to keep economic growth on track," said Supran.
In commodities trading, crude oil fell 15 cents, or 0.1 percent, to $104.55 a barrel. Gold climbed $6.90, or 0.5 percent, to $1,328.70 an ounce.
The dollar gained against the euro, but fell against the Japanese yen.
Among other stocks making big moves:
CF Industries rose $21.30, or 12 percent, to $202.30 after reports that Third Point, the hedge fund of the activist investor Daniel Loeb, had bought a stake in the company. Loeb disclosed the purchase in a quarterly letter to investors.