If offer is 25$--then stock will trade higher for that day and couple of days.
If 25$ offer is rejected,then Stock will go up to 25$,but how long does it stay above 25$ depends upon bidding co.
For Amlyin--The price kep fluctuating-up/down-until Ichan stepped in.--then it was up and up.
For HGSI--the price went up--but never went too far.Premium offered was close to 10% after the original bid.GSK owned part of HGSI already--but HGSI argument was it was very high a few months ago.But GSK did not accept that thesis.
I think this buyout is similar to Amylin--except Amylin had its own sales force in USA and its sales were over 500 mil.$. It was paid 7 billion$--pretty high premium to Sales.