As I wrote here last week, TV finance pundits regularly tells us that price moves are the result of "momentum," or "bargain buying," or "profit taking." Together, these labels are so widely applicable as to drain themselves of any real significance. So let us put themn aside and try some other route forward. On Tuesday, after the market closed, the wire services carried the following, “Morgan Stanley downgrades XYZ.” On Wednesday, nobody could be found to buy XYZ at the previous day’s price. Is that an answer to the question “why”? This is complicated. One line of argument would contend that the words “Morgan Stanley downgrades XYZ” didn’t tell the market anything the market didn’t already know. The headline allusion is actually to what some researcher paid by Morgan Stanley has said in a 30-page report. That report itself is most likely the compilation of publicly available data: John Smith (as we’ll call the analyst) with admirable industry ...