There exists abundant academic literature showing that momentum, i.e. a positive correlation between initial ranking of stocks by their past returns and subsequent returns, is pervasive across different markets and time periods.Although recent criticism speculates on the disappearing of momentum...

The stock market should fund promising new firms, thereby breeding competition, innovation, and economic growth. However, using three decades of data from 47 countries, we show that concentrated stock markets dominated by a small number of very successful firms are associated with less efficient...