jc1981,
It only correlates with some stocks. For an example GDN.
If the company is not a leaky boat, you will get nor for warning of an announcement. As I said look at the volume preceeding the 18th of January. No rise in volume - no rise in share price.
So I suspect you can expect the same to happen again (ie) an announcement for VLA will come without warning.
IMO
DYOR