I noticed some people using technical analysis in this thread, so I wanted to re-post something I wrote on that topic in another thread.
Academic research finds that most daily price movements are
random.
Here's an
academic study that compared five common technical trading strategies to random trading. It concluded:
"
Our main result, which is independent of the market considered, is that standard trading strategies and their algorithms, based on the past history of the time series, although have occasionally the chance to be successful inside small temporal windows, on a large temporal scale perform on average not better than the purely random strategy, which, on the other hand, is also much less volatile."
Another
study looked at 5,000 technical trading strategies and found none performed better than chance.
This is
a great study that simulated a stock market where prices moved 100% randomly. Lo and behold, they found some of technical traders' favourite patterns in the random data:
"
To demonstrate why traditional technical analysis falls short, we applied the standard methods to a synthetic market generated by a random walk. Although the market data is engineered to be pure noise, technical analysis "discovers" strong features such as accumulation/distribution patterns, upward and downward trends, support and resistance levels."
So, if you are using the tools of traditional technical analysis, you are probably attributing meaning to noise. These same patterns appear in completely random data.
Just because a technique appears to work once or a few times doesn’t mean it has a success rate better than chance. People could flip coins to decide whether a stock will go up and down, and many of them would have streaks of 7 or more successes in a row. That’s just statistics.
Confirmation bias,
the gambler's fallacy, and
survivorship bias often lead people to feel confident about techniques that perform no better than chance.
Apparently, some prominent proponents of technical analysis are also
advocates of astrology, and believe that astrology can be used to predict stock price movements. That's maybe a sign that technical analysis lacks scientific rigour.
You can also ask:
1) if traditional technical analysis worked, why wouldn't high-frequency trading algorithms have
arbitraged all the
alpha away by now? and
2) if it worked, why doesn't technical trading have a billionaire poster child, like Warren Buffett for value investing?
Also relevant:
The video is about how
alpha is elusive because a) the stock market is highly unpredictable and b) even more importantly, anytime anyone finds a way to non-randomly attain alpha, people just copy them and
arbitrage all the alpha away. That would of course apply to technical trading methods.