The Dow Jones Industrial Average (^DJI -0.98%) is up by a modest 13 points as of 12:40 p.m. EST. Boeing (BA 1.51%) jumped 1.2% as memories of last week's Dreamliner fires started to fade, adding an index-leading seven points to the Dow. But IBM (IBM -8.25%) always casts a big, blue shadow over the index, and the stock was just downgraded by influential megabank JPMorgan. IBM's 0.9% drop slashed 13 points off the Dow.

That's all fine and dandy, but the biggest news in Monday's market came from a company that isn't part of the Dow: Apple (AAPL 0.52%) plunged 3.4% after two independent reports showed Cupertino cutting parts orders for the iPhone 5 in the current quarter. The price drop destroyed about $14 billion of Apple's total market value. To put that number into perspective, consider that aluminum producer Alcoa (AA) is worth just $10 billion.

If Apple itself had been invited to the ultra-exclusive Dow club, today's plunge would have caused a massive 127-point drop. With a share price of roughly $500, Apple would instantly become the most influential stock on the Dow, far ahead of IBM at $200 and a plethora of tickers below the $100 mark.

The company isn't likely to join the Dow anytime soon, given the outlandish influence its elephantine share price would hold. I'm big on keeping things in perspective today:

Source: The Wall Street Journal.

IBM may be the kingpin of the Dow today, controlling 11% of the index's price swings, but Apple would simply point and laugh. Imagine Cupertino replacing minuscule Alcoa tomorrow; the newcomer would rule the Dow with a 22.4% value stake. Replacing IBM instead in a wholesale change of the big-ticket guard, Apple would command 24.4%.

This is why Apple will never join the Dow, short of a stock split or a substantial price drop. On a day like this, investors can thank their lucky stars for this quirk of the blue-chip index.