I was idly playing with some data that included a Favourites BSP graph when I thought I would look at it as a Financial Chart (let me point out I am not a financial chartist ... I just draw lines to fit what I seem to see!

Does the success or otherwise of previous favourites have a (maybe subconscious) effect on the price (popularity) of future favourites. Does 'the crowd' like/dislike favourites because of how successful they have seen them to be and influence the prices until they have become so influenced that they move into the realms of 'value'.
Could it be that Betfair review the BSP formula over time, the changes in trends are quite significant.
The graph is the return (no commission) on backing all favourites for 1 point since 01/01/2016 to date, GB and Ireland. all race types, all everything ... no filters.