Except, really, it doesn\’t.
The terms are five for 12 at 2.54 as opposed to the pre rights price of 4.91.
So 12 times 4.92 plus five times 2.54 divided by 17 gives us 4.21 as the theoretically correct (umm, odd theory I know) price for the shares after the announcement of the rights issue.
Overnight the shares were 3.99. A five percent or so fall from where they should have been then.
Yes, a fall, but not really a plunge I think? 5% is hardly the sort of volatility to write home about in current markets, is it?