Subject: Re: Maybe, the tide turned
My guess is that a "Coppeck sell" that occurs significantly above the zero line is not going to work out, since the market can recover and resume its uptrend without passing below the zero line that makes a "Coppeck buy" possible. Some kind of alternative buy signal is going to be required, I think.

You're right. It wasn't designed to be a sell signal anyway.

Even as a buy signal, it only works sporadically, for example it did not trigger at the end of 2018 and not even in March 2020, the Covid crash was too fast.

But - if the curve happens to to be negative when you look, and it starts going up, those seem to be good entry points for long term investments, historically.