MAX P0WER writes that the stock market’s non-reaction to the raising of the threat level to orange indicates that the color-coding and warning system has no credibility.

Probably. The other possibility is that the stock market has already reflected the same thing that the threat warning is reflecting: the vague sense that something might happen on the anniversary. In which case the market’s non-reaction would be, well, not exactly a sign that the warning system works, but a sign that the stock market is evaluating risks the same way. The real test will take place when and if the threat level goes up in an unforeseen fashion. If the market doesn’t react then, it’ll be much stronger evidence of the threat warning system’s uselessness.