“I don't see how you could dump 6 million shares onto this board...

“I don't see how you could dump 6 million shares onto this board unless you were managing both sides of the transaction”

The course of sales data for Friday shows that 1.49 million shares traded in special crossing or on Chi-x after the closing auction.
Special crossings are definitely prearranged.
And in the actual closing auction, 4.11 million shares were traded.
I am not sure exactly how that works but I expect that there could be some prior agreement between some of the participants to show up and take the price set by the auction.
On a gold mining index re-balance day, I remember seeing astounding volumes of NST traded in a closing auction.

Only 0.74 million PME shares were traded during the day on Friday prior to the closing auction.

Cheers