[twofornone]

Technical analysis sort of "works" in the same way that e.g. astrology "works", in that for any given plot of stock data, you can typically draw a of a number of technical patterns which seem to fit. I've never seen any convincing evidence to the contrary.

But one thing is for sure, if technical analysis works then a neural net will trivially pick up on existing strategies and although the cutting edge is always kept secret in the financial world, we probably would have heard of ML techniques rediscovering technical analysis by now if it were truly successful, since even an amateur could build and train a neural net from free data to learn technical analysis.

P.S. if simple technical analysis techniques ever worked, I also predict that they would quickly stop working as such arbitrages eventually disappear. You're not trading against news or patterns, ultimately, whether traders realize it or not, they are trading against mass financial psychology and HFT algos. Once neural net based training becomes the predominant tool, it will be interesting to see the collective patterns that emerge, likely totally disconnected from actual fundamentals. It may be chaotic, or it may be close to steady state, but it will definitely be in a state of flux as neural nets come online and constantly train on the latest patterns. It's a battle against the arrow of time.