Just because it's a noisy signal, doesn't mean it's not a signal. It has something to do with Canon, and where there is smoke there is fire. If the 5D3 was killing it, I doubt we'd see Canon's stock fall off so dramatically against the benchmarks. And if you look at the chart, the slide begins right after the release of the 5D3.
Either way, a stock price falling is a sign of trouble for a company. If a company is making bad decisions overall, there is a greater probability that any one decision, no matter how small, was bad.
This is the horrific ecomonics lesson I was referring to. And yes, it's troublesome. You first relate it to the release of the 5D Mark III (1st paragraph), which makes no sense but let's not go there. THEN, you try to generalize the stock price falling to the overall company performance and not necessarily the 5D3 but a whole slew of other things (2nd paragraph), which, negates your first statement and indicates that it can't possibly be just because of the 5D3. Which it can't be, but that's not what you said, then you sort of said it, and now nobody knows what the heck you're talking about and probably no longer cares.
Once again, can you show us data that directly implicates the 5D Mark III to Canon's stock prices falling? Out of all of the huge line of Canon products, it must be from the 5D Mark III right? If so, show us. Otherwise, this is just a load of garbage like most of this thread has turned in to.
If you knew all of the different factors that affect a company's stock performance, you wouldn't be making any of these statements. No offense against you, but you went personal in your last statement which also indicates your lack of class.
Just because you don't understand the lesson, doesn't make it any less true. You say that the decline in stock value gives us no information about the performance of the 5d3, I say it does. Even if the only thing that it tells us is that the overall company might be doing poorly.
Do political polls give us facts about general populations? No they give us a signal, within a certain degree of confidence. In this case, the falling stock performance(relative to benchmarks and peers) gives us a signal as to the overall state of affairs at Canon, of which the 5d3's performance constitutes some factor (however small).
Is it possible that the 5d3 is killing it while the rest of Canon is falling apart: YES! But there is nothing to support that.