Market Behavior under expected and unexpected news I found the following text in the paper "Real-time Price Discovery in Foreign Exchange"


  The general pattern is one of very quick exchange rate conditional mean adjustment, characterized by a jump immediately following the announcement, and little movement thereafter. Favorable U.S. “growth news” tends to produce dollar appreciation, and conversely. [...] [A] one standard deviation U.S. payroll employment surprise tends to appreciate (if positive) or depreciate (if negative) the dollar against the DM by 0.16 %.17 This is a sizeable move [...]


implying that this news are only available to the market once the announcement is made by the US authorities. Other similar announcements are considered: Retail Sales, Industrial Production, Consumer Credit, etc.

I am having trouble to understand why this is an acceptable explanation. From my point of view, the markets must "feel" the increase (decrease) and adjust accordingly before the announcement. Any price change after an announcement seem as irrational or herding behavior to me. On the other hand, I can think of examples in which a real surprise causes movements in the market: changes in Central Bank policy, social unrest, accidents, etc.

Am I missing something?
Short answer: the market has a forecast of the government numbers but the market considers the actual government numbers to contain information not available to the market. Therefore when unemployment  is lower than the market forecasts this indicates that on average things will be better than than the market forecast before the release. This is not to say that the forecast has no use, nor that the government number is perfect. Instead, it merely requires that there be some information in the release not in the forecast such that differences from the forecast are informative.