A Eficiência do Mercado Financeiro

Um artigo de Sebastian Mallaby, sobre a eficiência do mercado financeiro : ""Efficient" means that all information is reflected in prices; you should get moves only in response to new information. But no stunning news explained last week's jump in volatility. Alan Greenspan gave an anxious speech, but anyone with half an eye on mortgage defaults should have felt anxious already. China's stocks fell, but a small market that largely excludes foreigners need not have spooked investors in London or New York.

The truth is that market sentiment shifted for no satisfying reason. One day investors made light of storm clouds; the next day they yelled in terror. But the remarkable thing is that, despite this capricious behavior, no denunciations of markets or speculators emanated from Congress. Sen. Chuck Grassley (R-Iowa), who had recently growled about the secrecy of hedge funds, was not moved to say anything. Democrats, who might have been expected to condemn (again) the idea of putting Social Security money in the stock market, stayed silent.

This was all good, but it was not all predictable. In most eras and in most countries, bouts of market chaos provoke outbursts of market skepticism."