This morning's news that an analyst downgraded Apple's stock from "buy" to "neutral" should worry more than just Apple fanboys. Apple's stock has gotten so omnipotent than a tumble would hurt us all. Since surpassing Exxon as the most valuable company in the world, Apple's continued its market domination, breaking "all time high" records for the last 8 months. Last September, for example, Apple made headlines when its stock reached $411.50, a previous record from July's $403.41 price. Today, the price's hovering around $635. Those with a stake in this stock will delight in this growth. But it may have reached a point where the stock is too dominant. If it fails, everything else will tumble, too. 

Having a super strong stock, like Apple, in one's portfolio has benefits as well as dangers. The good side is obvious: It makes lots of money. But, it also means what happens to Apple can have a big (maybe bad) effect on the overall portfolio, as Reuters' David Randall explained back in March. "As Apple stock has marched higher, well-timed bets on the company have helped some growth-oriented and blended mutual funds outperform the broad market," he writes. "But in doing so, many of those funds have now tied investor dollars closer to the performance of a single company." It ruins that whole diversification idea. A mixture of that once seemed safe, reducing risk across a bunch of different companies, now depends on one big company. Now, with Apple's constant up trajectory, that makes investors happy. But, if Apple's stock tumbles, those portfolios will crash with it. "It adds to the risk profile of a fund to have a significant stake in one stock because it makes them more susceptible to bad news on one or two stocks and they won't be able to cushion the blow with diversification,"  Todd Rosenbluth, a senior fund analyst at Standard & Poor's Capital IQ, told Randall. 

Many of these types of portfolios have integrated the tech behemoth. It's the sixth most popular holding in 401(k) plans, reports Randall and makes up almost 9 percent of Fidelity's Contrafund. Looking through your own 401 (k) plan you might be surprised to see how much Apple shows up in the "broad market" funds. If Apple falls, these "safe" retirement funds won't look so good anymore.

Speculation that Apple will fall due to the growing toll subsidies have on carriers, as floated by Walter Piecyk, the analyst for BTIG, could turn out to be totally off base, of course. Verizon, AT&T and Sprint subsidize the price of each iPhone to attract customers, losing around $400 per phone sold. Carriers have indicated they might fight back. Piecyk thinks this will make Apple's stock less desirable. Like all guesses, even educated ones, this could turn out false. Plus, the dividend buyback Apple just announced, makes the stock more valuable, some argue. But, even if it doesn't happen in the next few quarters, as the laws of physics dictate, what goes up, must come down.