Global information spillovers
The amount of information produced in an economy varies over time. Stock prices in particular are informative but their degree of informativeness changes over time. Agents do not produce the same amount of information in every macroeconomic state of the world or in anticipation of every state. Although a baseline level of information is always produced spending additional resources on information production is not always beneficial. In fact it is so only when the expected benefits exceed the costs. In particular more information is produced when distinguishing between firms is more important.