I’ve said before about how I’m not sold on technical analysis being viable, but I’ve seen counter-arguments floating around that say “it doesn’t matter if TA doesn’t make sense, if people believe it and act on it then it will still move the markets.” In this case, knowing TA yourself lets you read the minds of all the other TA-knowers and join in their pumps and their dumps, making money by being part of the crowd. Yet fundamental analysis says that there is an underlying “fair value” for an asset, and good investing is about going long on undervalued assets and short on overvalued ones. Fundamental analysis accepts the possibility of hype and speculation, “the market can stay irrational longer than you can stay solvent” etc, but it requires that at SOME point things fall back to earth and assets reach their fair value.

Technical analysis on the other hand implies that the future price of a stock is most strongly connected to its previous prices, not to the value of the underlying asset. This means that previous highs, lows, and averages give a kind of momentum that can be predicted and traded on.

My question is, how can these both be true? Technical analysis assumes that the price reflects all available information, otherwise past trends cannot predict future prices. Fundamental analysis assumes that the price does not reflect all available information, otherwise there are no over-valued or under-valued stocks and all stocks are at their fair value.

How can the price of a stock be dependent both on the analysis of the underlying asset AND on the previous prices of the stock, since those can easily move in opposite directions? If there is a conflict between the TA and the FA, who wins? Well if you believe the Efficient Market Hypothesis, neither win because the winning move is to buy once and hold forever. But if you believe FA then FA wins and the price must go up, if you believe TA then TA wins, but I don’t think both can be true in all or most cases.

I’d like to know if anyone believes both TA and FA can be true and if so why.

As an aside, Wikipedia explicitly labels Technical Analysis as a pseudoscience.