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.

Another day passed on Wall Street -- and across the world, for that matter -- without a firm outline from the White House on how it plans to handle the Syrian situation. One way that President Obama plans to not deal with it is by putting U.S. troops on the ground -- but by no means did that rally the market. The S&P 500 Index (SNPINDEX:^GSPC) lost five points, or 0.3%, ending at 1,632, as August ended up being the worst month for the S&P in 15 months. 

Advanced Micro Devices (NASDAQ:AMD) had a rough week all around, seeing its market cap get a 10.4% haircut in the last five sessions alone. The stock fell 3.3% Friday, just after research firm IDC shared its stubbornly bearish views about the PC market in the years to come. We've seen the headlines about the PC's decline in the U.S., but yesterday's IDC report suggested that sales would also start falling rapidly in emerging markets in the near future. 

Homebuilder DR Horton (NYSE:DHI), which, just yesterday, was one of the S&P's 3 Best Stocks, lost 3% Friday in a swift reversal of fortune. The big catalyst behind DR Horton's jump Thursday was the news that 30-year fixed-rate mortgages pulled back to a 4.51% rate, making it easier for the buyers who keep DR Horton in business to afford a home. 

Today, the rates on treasury bonds eased back up a bit, and DR Horton peer PulteGroup (NYSE:PHM) fell victim to the same resultant decline as DR Horton, stumbling 3%. Strangely enough, PulteGroup also shared the limelight with DR Horton yesterday as one of the S&P's three brightest shiners. While interest rates are vitally important to keep track of as an investor in either of the latter two companies, if there's a long-term housing and economic boom anywhere in the near future, these two companies shouldn't be appearing on this list very often.

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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