Technical Analysis: Quotes

Trends might tend to perpetuate themselves for either of two reasons:
1) crowd instinct of mass psychology, jumping on the bandwagon, self-fulfilling prophecy
2) unequal access to fundamental information about a company, leading to a gradual increase in the price

"The statement "market action discounts everything" forms what is probably the cornerstone of technical analysis. [...] The technician believes that anything that can possibly affect the price--fundamentally, politically, psychologically, or otherwise--is actually reflected in the price of that market."
Murphy (1999)

"The evidence suggests that technical analysis by itself is not a good predictor of future returns."
Singal (2004)

"There have been long periods in the past when trading rules would have provided valuable information about future prices. However, their value has not been demonstrated in recent years."
Taylor (2005) page 157