The Dow Jones Industrial Average (DJINDICES:^DJI) average is moving lower today. As of 12:30 p.m. EDT, it is at 13,555, down 24.08 points, or 0.18%. The other major indexes are also sliding: The S&P 500 (SNPINDEX:^GSPC) is down 0.31%, and the Nasdaq is down 0.73%.

While Apple reportedly sold more than 5 million iPhone 5s on the first weekend, analysts were expecting more, and this miss may be a main catalyst for the markets' malaise. Apple represents 5% of the S&P 500 and has a huge influence on the technology sector as a whole. While it is not part of the Dow, Apple's influence can be seen on Dow components Microsoft (NASDAQ:MSFT), Hewlett-Packard (NYSE:HPQ), and Intel (NASDAQ:INTC) -- three companies that are currently weighing the index down.

So why are they down?
While Apple's iPhone 5 sales miss could be seen as a good thing for Microsoft investors, it could also prove an ill omen, as this may be the beginning of a growth slowdown in the smartphone industry. The number of smartphones has exploded over the past few years, and with Microsoft's Windows Phone soon to hit the market, investors may be concerned with its potential. If the all-mighty iPhone can't hit its sales numbers, what will the Windows Phone do? Currently Microsoft is down by 1.45%.

As smartphones and tablets have become the new must-have devices, PC sales have taken a beating over the past few years. Hewlett-Packard and chip maker Intel have both seen sales decline. If the slowdown in smartphone has started, the pullback from PCs may be greater than previously expected. The market has shaved HP by another 2.02% today and hit Intel by more than 1.84%.

Fool Contributor Matt Thalman owns shares of Apple and Microsoft. The Motley Fool owns shares of Microsoft, Apple, and Intel. Motley Fool newsletter services have recommended buying shares of Apple, Microsoft, and Intel. Motley Fool newsletter services have recommended creating a synthetic covered call position in Microsoft. Motley Fool newsletter services have recommended creating a bull call spread position in Apple. The Motley Fool has a disclosure policy.

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