This is purely on a hunch, I might run my calculations later on.
Price crash from Friday doesn't make much sense and index re-balance announcement could be just a decoy, as big funds already got out earlier (they don't need to wait for S&P's announcement to know what will happen).
I reckon that ISD could be still a takeover target, wishful thinking is that directors are not buying - because they are not allowed.
ISD Price at posting:
21.3¢ Sentiment: Hold Disclosure: Not Held