another fund reduce their holding, page-33

I saw it hc99 but I wonder if it is genuinely large buy orders in the hope that Vanguard or other big seller sells into it or is it the large seller trying to make the buy side look better in the hope that other buyers jump the queue so the big seller can offload for a higher price.
Early this morning I saw an order for 1,000,000 jump in the buy queue for a moment before disappearing right before things started heading south.