Although we don't believe in timing the market or panicking over market movements, we do like to keep an eye on big changes -- just in case they're material to our investing thesis.

Unlike yesterday, economic data was front and center as the primary driver of equities. With earnings season beginning to wind down, investors are once again turning their attention to the health of the U.S. economy.

The big news today that had investors a bit shaky at first was U.S. retail sales data, which came in with 0.2% growth for July compared with estimates that had called for 0.1% contraction. On the bright side, retail sales growth leading into the back-to-school shopping season may be stronger than expected, which is great news for retailers. Conversely, retail sales growth of just 0.2% is down from 0.6% last month and also reminds investors that the state of U.S. consumer spending is still shaky at best.

By the end of the day, the broad-based S&P 500 (SNPINDEX:^GSPC) had digested the double-edged sword that was the retail sales figure and trudged higher by 4.69 points (0.28%) to close at 1,694.16 -- just the index's second up day in the past seven trading sessions.

Leading the charge higher today was memory-chip maker Micron Technology (NASDAQ:MU), which advanced 8.2% after analysts at Wedbush Securities, RBC Capital, and Williams Financial Group spoke positively about the company following its completed purchase of Elpida Memory. Micron also announced that it will be trimming about 5% of its workforce, which currently totals around 30,000. With Micron seeing higher DRAM prices, improving market share, and lower expenses, it isn't hard to understand why the company is hitting another fresh 52-week high today.

Technology juggernaut Apple (NASDAQ:AAPL) is once again flirting with $500, up 4.8% on the day, after activist investor Carl Icahn revealed a "large position" in the company. Icahn believes Apple shares to be significantly undervalued and is publicly encouraging the company to repurchase shares while he believes they remain cheap. Icahn has been a very public shareholder advocate in the middle of the ongoing Dell (UNKNOWN:DELL.DL) private buyout attempt where he holds the second-largest position next to CEO and co-founder Michael Dell, and was a big contrarian investor who made quite the killing on Netflix when it dropped back under $100 a share. He has a generally good history of creating shareholder value, and Apple investors should certainly be thrilled to see him on board.

Finally, futures exchange operator CME Group (NASDAQ:CME) jumped 4% despite no company-specific news -- at least today, that is. Over the past couple of trading sessions, though, we learned that futures volume in global crude and Brent trading has been at record levels, which will serve well for CME's transaction fees come earnings time. CME is a company that will benefit from any form of trading volatility and skepticism, so with U.S. markets perched very near all-time highs and the Federal Reserve contemplating the paring back of its monetary easing program, CME's future contracts volume could be ripe for a big surge.

Fool contributor Sean Williams owns shares of Dell but has no material interest in any other companies mentioned in this article. You can follow him on CAPS under the screen name TMFUltraLong, track every pick he makes under the screen name TrackUltraLong, and check him out on Twitter, where he goes by the handle @TMFUltraLong.

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