With IBM (NYSE:IBM), the largest component of the Dow Jones Industrial Average (Index: ^DJI), having lost almost 8% of its value, the blue-chip index is down 0.12% as of 1:25 p.m. EDT. Meanwhile, the S&P 500 (SNPINDEX:^GSPC) is up 0.67% to 1,552.

The Dow Jones Industrial Average is weighted solely by stock price, so IBM, with its $191 stock price, is the largest component of the Dow, with a weighting of nearly 11%. Chevron and 3M are second and third with respective weightings of 6% and 5.5%. I find that the S&P 500 is a much more useful measure of the market, as it is weighted by companies' market caps. However, the Dow is far more popular because it has been around longer.

IBM has plummeted today after it reported worse-than-expected earnings last night. The company reported earnings per share, excluding one-time items, of $3, short of analyst expectations of $3.05. Revenue of $23.4 billion missed analyst expectations of $24.7 billion. The company kept its full-year earnings guidance constant at $15.53. The earnings report is worrisome, as revenue was down or flat across all of the company's major business segments.

Today's Dow leader
Today's Dow leader is Microsoft (NASDAQ:MSFT), up 3.2%. Microsoft and other tech stock were hit hard last week after market research firm IDC reported that PC sales were far worse than expected in the first quarter of the year. While the report put much of the blame on smartphones and tablets, the researcher also blamed Microsoft's Windows 8 operating system for deterring consumers from buying new PCs. The report led many investors to believe that Microsoft would have a weak quarter like many other technology stocks are having.

Last night, Microsoft reported earnings that broke technology stocks' streak of disappointing earnings. The company reported EPS growth of 18% to $0.72, beating Wall Street forecasts of $0.68, while revenue growth of 18% to $20.5 billion was right in line with expectations.

The Windows division took in revenue of $5.7 billion, up 23% from last year. At first glance, this would seem to fly in the face of the IDC report. However, if you adjust revenue for the company's Windows Upgrade Offer, which deferred revenue until this year, then Windows revenue was unchanged from the year-ago quarter.

While Windows 8 isn't doing the company any favors in the sales department, the division is still massively profitable, with an operating income of $3.5 billion in the first quarter. The other big driver is Microsoft's business division, which reported operating income of $4.1 billion -- though that was also boosted by deferred revenue from an earlier upgrade offer.