[isatrader]

Hi Isa,
I was reading that this Friday was an event called quadruple witching, where many funds re-balance their portfolios for the indexes they have to match. So there were several companies with large trade blocks during the closing hours of trading in the US.

[edit]
I just read some more about quadruple witching and it's not directly related to funds re-balancing, but it seems that Friday also coincided with quadruple witching plus fund rebalancing.

Thanks diaz, that's good to know.