It does not seem like anything. The holy grail is understanding the market sufficient to be part of the 9%(that, yes, means understanding all the systems). At that stage the Holy Grail is the market itself. However, the market is constantly and always changing so that it looks like anything besides what it's... a series of events with progr built around it.

To say that God does or does not exist is just like stating the Holy Grail does or does not exist. 'God' is just a partial understanding of the universe... but enough it can work for your individual. So also the Holy Grail is just a partial understanding of the market... However enough to make it function for your individual. Since it doesn't seem like any particular thing you can not go searching for this unless you already know what you are looking for.

Perhaps this will help others to observe some of it. I know it was one of the first things to 'click' for me personally.

I also happily challenge any aspiring Grail contender to inform me if it is.