Social Media and Efficient Markets

Does Twitter make sell-side analysts better?
The answer, according to a new study, is yes.
Analysts are generally overly optimistic when presenting earnings forecasts (largely due to incentives).
As information technology has proliferated, the competition for information production has increased.
Negative and positive information are treated differently by human psychology – the former being valued more highly.
Analysts looking at Twitter succumb to this asymmetry, biasing their forecasts downwards i.e. negating their over optimism.
These are fascinating results (there a few others in the article).