Stocks traded underwater for most of today's session, but a late-day rally took both the S&P 500 and Dow Jones Industrial Average (DJINDICES:^DJI) to record closing highs. The S&P finished up 0.2% to close at 1,923.57, while the blue chips added another 0.1%, or 18 points, to close at 16,717. Today was also the last trading day in May, and stocks racked up their fourth-straight monthly gain. Severe winter weather momentarily threw the economy off track, but failed to deter investors. And recent economic reports have come in much stronger, indicating the economy is growing robustly this spring. Bond rates also remain low, encouraging investors into stocks, but concerns linger about the market's valuation after last year's big gains.

Today, the Chicago PMI showed a strong expansion in manufacturing activity as the index increased from 63.0 to 65.5, better than estimates at 60.3, and indicating a robust expansion in that sector. Order backlogs also rose to a three-year high in May, indicating that activity should remain strong. Gains in the labor market and an improving consumer outlook seem to be finally trickling down to the industrial sector, as the durable-goods report earlier this week also showed surprising growth.

Elsewhere, consumer confidence fell slightly in May according to the University of Michigan's report, whose index came in at 81.9, below April's total at 84.1, but still ahead of estimates at 81.4. Consumers' primary concern was wage growth, though a majority of consumers said the economy had improved. Consumer spending also dropped by 0.1% in April, but that followed 1% growth in March, indicating the slide is likely to be temporary. 

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Among stocks gaining today was Madison Square Garden (NASDAQ:MSG), which moved up 3.3% after the New York Rangers advanced to the Stanley Cup Finals, and Steve Ballmer, the former Microsoft CEO, reportedly agreed to buy the Los Angeles Clippers for $2 billion. MSG owns the Rangers and the New York Knicks, as well as several media outlets engaged in broadcasting sports and other entertainment. While the Rangers' ascension to the Stanley Cup Finals is good news for the company, providing a national spotlight to the NHL team and another series' worth of media and ticket revenues, it's the Clippers' deal that's the juicy part of the story here. Ballmer's $2 billion offer would be one of the biggest in sports history, and makes MSG, at a market cap just north of $4 billion, look like a bargain if the arguably more prestigious Knicks were valued similarly. Ballmer seems to be the winner in a hot bidding contest, which has underscored the skyrocketing value of professional sports teams, as there are a limited number of them. The current owner, Donald Sterling, who was forced to sell the team after racist comments he made went public, purchased it for just $12 million in 1981. If those price tags continue to increase, MSG could be a steal at today's price.  

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Jeremy Bowman has no position in any stocks mentioned. The Motley Fool owns shares of Madison Square Garden. Try any of our Foolish newsletter services free for 30 days. We Fools may not all hold the same opinions, but we all believe that considering a diverse range of insights makes us better investors. The Motley Fool has a disclosure policy.