Everyone wants to create a story for why Apple’s stock dropped more than 6% today. While daily stock fluctuations are hardly worth mentioning, a 6% drop on seemingly no news does stand out as an outlier.

I have difficulty believing that a stock moves up or down on a specific news item because I am unable to verify why everyone is selling (and buying) a particular stock. Those selling shares at 9:30 AM may have a completely different motive compared to those selling at 3:59 PM. The same philosophy applies for a stock on the rise.

As Apple’s stock collapsed throughout the day, news sites were fumbling over each other trying to guess what could possibly cause Apple shares to fall. Several reasons floated around the web included:

1) A DigiTimes Article. I assume this article talked about all iPhone production coming to a halt, because I have a hard time thinking of any other topic that can cut $30 billion of Apple market cap in a few hours.

2) Tax Selling. This one just won’t die. Are investors selling their Apple shares today (25% off the high) only to avoid paying 5% more taxes on dividends and maybe 5-10% more for long-term capital gains?

3) China Mobile Approves a Nokia Phone. So Apple loses $30 billion of market cap in a few hours because China Mobile announces it will sell a Windows Phone made by Nokia? Really?

4) Samsung is Crushing Apple. Let me guess. Teens are ditching their iPhones and iPads and switching to Samsung phones because they are just that cool. Surely that would cause Apple to lose $30 billion of market cap in a few hours.

5) Some rumor about retail margin requirements being increased for only one stock; Apple. At first glance, this one at least sounds somewhat plausible, until one realizes most individual investors highly levered with margin already faced tough times a few weeks ago when the stock crashed to $505. Even if this rumor was true, individual investors would be unable to account for $30 billion of Apple value vanishing in a day.

6) Apple Maps. If all else fails, blame Apple Maps (ok…maybe I was the one to tweet this one as an excuse for Apple’s drop).

All of these possible explanations for today’s stock drop are nothing more than attempts of adding context to mystery; creating a story out of the unknown. Unfortunately, many are missing the big picture.

There are very few news items that are even capable of moving Apple’s stock price by 6% in a day (the worst daily decline in years). Such a move is typically left for monumental events such as a CEO departure or natural disaster impacting production or distribution, and even then those events would often be met with a rush of buyers willing to support the stock.

Is there anything we know for sure about today’s price action? Yes.

For every trade, the marketplace needs a buyer and seller. A stock price is the equilibrium where a buyer and seller are willing to exchange a share. Today, sellers were outnumbering buyers at $569 (Apple’s stock price at 9:31 AM), so the marketplace had to lower the price until sellers and buyers were in equilibrium. At 3:59 PM, the equilibrium for Apple’s shares was down to $538. Selling pressure remained elevated for most of the day, and as the share price declined further, additional selling pressure came in, forcing the shares to fall even more. Apple shares haven’t seen this type of price action in years (the typical retracement was only around 15%, which would take a few weeks to occur). Buyers would typical come in and support the stock (the Flash Crash of 2010 stands out as another notable exception).

The next question is what caused all of this selling? Unfortunately, we are forced to think of possible reasons for the selling to create a story because we hate the unknown. I could end this post right here and call it a day, but what’s the fun in that? Sometimes even I need a story or two.

I’m skeptical that any rumored (or even factual) news story was capable of causing the world’s most valuable company to drop 6% in a few hours. Instead, I think the intense selling pressure was caused by several mid-sized hedge funds forced to sell Apple positions because their computer models were programmed to sell Apple. In an effort to remove emotion from trading, some funds program models to buy and sell stock given certain market conditions (most likely momentum characteristics). By removing the human from the equation, one is unable to avoid selling a stock on no news (in many ways, for the model to be successful, all decisions have to be followed). I think a rather large fund (or a few) were forced to liquidate or reduce their Apple positions simply because the stock was in collapse mode. Add in differing degrees of leverage (money borrowing) and you can see how things can snowball out of control very quickly. I also believe a similar thing happened last month when Apple shares fell 8% in only two days. The harder Apple fell, the faster the models said sell. Meanwhile, buyers were simply unable to outnumber the sellers, causing the equilibrium price to remain under pressure. Of course, I’m sure there were plenty of retail investors selling Apple shares for completely different reasons, which supports my skepticism for labeling specific news items as stock price drivers.

Looking at the long-term, Apple is facing several headwinds that may give buyers pause. I have a difficult time modeling much in the way of EPS growth in 2013 given tough year-over-year margin comparisons. In addition, recent Apple management changes have not been tested in the marketplace. I’m sure one can also come up with a few other things that would elicit fear about Apple’s future, but at a certain price and after a set amount of time, these fears are fully realized and digested by the market. I suppose one can also come up with good scenarios for Apple, but what’s the fun in that? When Apple’s stock plunges on heavy volume, skepticism should take hold, helping to usher in clear thoughts. Short-term stock trading is a fool’s game and I would love to be proven wrong.