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.

If you take a look at the Dow Jones Industrial Average (^DJI 0.56%) today, you'll find that two of the index's three worst performers come from the tech sector. Not only that, but the biggest losers team up to form the famous Wintel duo. Microsoft (MSFT -1.27%), the inventor of the Windows operating system, plunged as much as 2.4% overnight, while Intel (INTC -2.40%) lost 1.9% at most.

These two stocks often fall and rise in tandem based on the same catalysts, but that's not the case today. Intel is falling for one distinct reason; Microsoft shares suffer from a different malaise.

Personnel issues
For Intel, it's a pretty clear-cut reaction to bad news from the executive suite. David "Dadi" Perlmutter, Intel's chief of architecture (chip designs, not buildings), is leaving Intel in February to close out a career spanning more than three decades.

David Perlmutter, soon to be former head of Intel's architecture group. Image source: Intel.

Perlmutter has been a driving force behind Intel's microprocessor design choices since the early 1990s. When he directed the development of the Pentium Pro and Pentium II processors. He's an industry legend who had his sights on Intel's CEO office when Paul Otellini retired earlier this year.

But he was passed over for then-COO Brian Krzanich, who immediately reduced Perlmutter's power base within Intel. Today's resignation might be seen as the endgame to Intel's CEO search, pushing one highly qualified candidate away in bitter disappointment.

Intel will have Perlmutter on board to smooth out the transition until February, so it's not a clean break with a boot print on Dadi's backside. Still, Intel is losing a valuable human resource and heading into uncharted waters when it comes to big-picture architecture choices. Investors are feeling the pain today.

Worrying about the near future
For Microsoft, the pain points are twofold.

First, Microsoft's brand-new Surface 2 tablet launched to widespread indifference. According to Global Equities Research analyst Trip Chowdhry, early sales of the new tablet were "lukewarm" and Microsoft stores in Silicon valley saw "extremely light" foot traffic.

If this was Microsoft's attempt to steal the thunder from Apple's (AAPL -1.22%) unveiling of its latest iPad updates on the same day, it was a miserable failure.

Apple CEO Tim Cook did take a few seconds out of his iPad presentation to poke fun at competing tablets, and Microsoft's Surface line specifically. I guess that's a win if you believe that "any publicity is good publicity," but Microsoft investors don't -- and shouldn't -- see it that way. Any reasonable way you slice the Surface 2 launch, Apple walks away as the clear winner in this duel over consumer hearts and minds.

Furthermore, Microsoft investors are bracing for even more bad news on Thursday night. That's when Microsoft reports second-quarter results, and early signs don't look good.

Analyst estimates point to earnings of $0.54 per share on $17.8 billion in sales. That would be an almost flat bottom-line performance compared to the year-ago period, along with 11% higher revenue. But those earnings estimates have been lowered from $0.56 per share over the last two months, and Intel didn't provide much comfort in last week's earnings update.

Microsoft is setting itself up to beat current expectations but follow up with weak guidance for the crucial holiday quarter -- just like Intel. Investors' nerves are starting to rattle, and it shows in Microsoft's share prices.

That's how Intel and Microsoft came to lead the Dow downward today, along very different paths.