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

Just like Wall Street's two other major indexes, the S&P 500 Index (SNPINDEX:^GSPC) stumbled Monday in the last hour of trading, ending in the red after what had looked like a modestly bullish day. A growing sense that the U.S. is heading toward military intervention in Syria sent stocks lower, as Secretary of State John Kerry asserted that "President Obama believes there must be accountability" for the use of chemical weapons on Syrian civilians last week. The S&P ended the day off 6 points, or 0.4%, ending at 1,656. 

Archer-Daniels-Midland (NYSE:ADM) shed 4.9% today, as a highly volatile commodities market hits the agricultural giant today. The price of soybeans and corn soared 4.6% and 6.5%, respectively, on Monday. While higher prices may ostensibly benefit ADM, there's a flip side to that coin if prices rise too quickly. The company's corn processing division, for instance, sells sweeteners and other corn-based products to the food and beverage industry, which, faced with rising commodities, could move to substitute products. 

Autodesk (NASDAQ:ADSK), which popped 7.7% on Friday to end as one of the day's 3 Best Stocks, lost 2.6% Monday as shares pulled back from the euphoric highs reached last week. The unbridled optimism Wall Street expressed after Autodesk's second-quarter earnings was tempered by the inconvenient reality of the situation today, which sees the stock trading at 40 times earnings despite negative earnings growth in its last quarter.

Lastly, Visa's (NYSE:V) stock fell 2.3% Monday, as litigation regarding debit card swipe fees makes its way through the courts. The Federal Reserve is appealing District Court Judge Richard Leon's decision, which ruled that the Fed's $0.21 cap on debit card transaction fees was arbitrary and illegal, and that the cap failed to spark competition between payment networks. The Fed hopes to expedite the appeals process as Visa and other credit card companies anxiously await the next ruling.

Fool contributor John Divine has no position in any stocks mentioned. You can follow him on Twitter, @divinebizkid, and on Motley Fool CAPS, @TMFDivine.

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