As the graph shows, other than a brief if rather spectacular peak during the dotcom boom, the FTSE Aim All-share index has persistently under-performed the FTSE 100 index ever since its creation.
I dunno….quite literally, I don\’t know. But let me put forward this as an idea:
Over the past year, Aim has waved goodbye to stellar performers such as Domino\’s Pizza and Spice, which have moved up to the main market.
If the companies that perform really well leave the market to go up to a main listing, then the market index isn\’t really going to be measuring quite the same thing as that main market index, which doesn\’t have anywhere higher for successful companies to go to, does it?
It\’s not quite survivor bias, but it is something a little like that, no?