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Previous issue date: 2012-02-16 === The Behavioral Finance develop as it is perceived anomalies in these markets efficient. This
fields of study can be grouped into three major groups: heuristic bias, tying the shape and
inefficient markets. The present study focuses on issues concerning the heuristics of
representativeness and anchoring. This study aimed to identify the then under-reaction and
over-reaction, as well as the existence of symmetry in the active first and second line of the
Brazilian stock market. For this, it will be use the Fuzzy Logic and the indicators that classify
groups studied from the Discriminant Analysis. The highest present, indicator in the period
studied, was the Liabilities / Equity, demonstrating the importance of the moment to
discriminate the assets to be considered "winners" and "losers." Note that in the MLCX biases
over-reaction is concentrated in the period of financial crisis, and in the remaining periods of
statistically significant biases, are obtained by sub-reactions. The latter would be in times of
moderate levels of uncertainty. In the Small Caps the behavioral responses in 2005 and 2007
occur in reverse to those observed in the Mid-Large Cap. Now in times of crisis would have a
marked conservatism while near the end of trading on the Bovespa speaker, accompanied by
an increase of negotiations, there is an overreaction by investors. The other heuristics in
SMLL occurred at the end of the period studied, this being a under-reaction and the other a
over-reaction and the second occurring in a period of financial-economic more positive than
the first. As regards the under / over-reactivity in both types, there is detected a predominance
of either, which probably be different in the context in MLCX without crisis. For the period in
which such phenomena occur in a statistically significant to note that, in most cases, such
phenomena occur during the periods for MLCX while in SMLL not only biases are less
present as there is no concentration of these at any time . Given the above, it is believed that
while detecting the presence of bias behavior at certain times, these do not tend to appear to a
specific type or heuristics and while there were some indications of a seasonal pattern in Mid-
Large Caps, the same behavior does not seem to be repeated in Small Caps. The tests would
then suggest that momentary failures in the Efficient Market Hypothesis when tested in semistrong
form as stated by Behavioral Finance. This result confirms the theory by stating that
not only rationality, but also human irrationality, is limited because it would act rationally in
many circumstances === As Finan?as Comportamentais desenvolvem-se ? medida em que s?o percebidas anomalias
nos ditos mercados eficientes. Seus campos de estudos podem ser reunidos em tr?s grandes
grupos: vi?s heur?stico, subordina??o a forma e mercados ineficientes. O presente estudo
foca-se em quest?es relativas ?s heur?sticas da representatividade e do ancoramento. O
presente trabalho objetivou ent?o identificar a sub-rea??o e sobre-rea??o, assim como a
exist?ncia de simetria nos ativos de primeira e segunda linha do mercado acion?rio brasileiro.
Para tal foi utilizada a L?gica Fuzzy e os indicadores que classificam os grupos, estudados a
partir da An?lise Discriminante. O ?ndice mais presente, nos per?odos estudados, foi o de
Exig?vel/Patrim?nio L?quido, demonstrando a import?ncia deste no momento de discriminar
os ativos a serem considerados vencedores e perdedores . Nota-se na MLCX que os vieses
de sobre-rea??o se concentram no per?odo da crise financeira, sendo que nos demais per?odos,
de vieses significantes estatisticamente, s?o obtidas sub-rea??es. Estas ?ltimas se dariam em
momentos de n?veis moderados de incertezas. Nas Small Caps as rea??es comportamentais
em 2005 e 2007 ocorrem de forma inversa ?s observadas nas Mid-Large Caps. Agora em
momentos de crise ter-se-ia um marcado conservadorismo enquanto que nas proximidades do
fim do preg?o viva-voz da Bovespa, acompanhado do aumento das negocia??es realizadas,
nota-se uma rea??o excessiva por parte dos investidores. As demais heur?sticas nas SMLL
ocorreram no final do per?odo em estudo, sendo esta uma de sub e outra de sobre-rea??o e a
segunda ocorrendo em um per?odo financeiro-econ?mico mais positivo que a primeira. No
que diz respeito a sub/sobre-rea??o em ambos tipos, n?o se detecta a predomin?ncia de
nenhum destes, fato que provavelmente seria diferente nas MLCX em um contexto sem crise.
Quanto ao per?odo em que tais fen?menos se d?o de forma significante estatisticamente notase
que, em sua maioria, tais fen?menos ocorrem nos ?ltimos per?odos para as MLCX
enquanto nas SMLL n?o apenas os vieses s?o menos presentes como tamb?m n?o h?
concentra??o destes em nenhum per?odo. Diante do exposto, acredita-se que, embora detectese
a presen?a de vieses comportamentais em certos per?odos, estes n?o aparentam tender a um
tipo espec?fico de heur?stica ou e embora existam alguns ind?cios de uma sazonalidade nas
Mid-Lage Caps, este mesmo comportamento n?o parece se repetir nas Small Caps. Os testes
realizados sugerem ent?o que haveriam falhas moment?neas na Hip?tese de Mercados
Eficientes quando testada em sua forma semi-forte conforme afirmado pelas Finan?as
Comportamentais. Este resultado corrobora com a teoria ao afirmar que n?o apenas a
racionalidade, mas tamb?m a irracionalidade humana, ? limitada, pois agir-se-ia
racionalmente em in?meras circunst?ncias
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