Fund Managers would have anticipated a move into ASX100, and...

Fund Managers would have anticipated a move into ASX100, and probably started to build a partial position, now that they have a foothold, they probably accumulating the rest of their position to reflect the index.

With that accumulation comes the usual games.

Lynas is a good example, it took off a month later.

AGO got two gaps lower at $3.48 and $3.35.

Also got a higher gap $3.73.

Imo $3.73 will get closed first.