Trade volumes

Can anyone figure out why this has spiked recently?

Average volumes ~270k shares traded a day for this year, but last 4 days has been much much higher (and driven by big parcels).

Today a parcel of 880k shares traded in seemingly 1 block trade (I recall on the 16th there was a similar trade for ~1.4m shares), but no notice of change in significant shareholder notices.

The positive thing is that its not depressing the price, but seems unusual.