Also, Because ZFX is public listed company and their investment...

Also, Because ZFX is public listed company and their investment has to look good.

So after the take over bid, they may want to buy the share price up (only small percentage shares left). Because not many share left and they know the company is worth much more than what they paid for after the production commencing. Also, when the total value of the company is up sizably, they are easier to deal with their own share holders, financial institutions and public. They have every reasons want to the price up than going down or de-list the company.

Also, in majority of cases, after the take over or merger, the share price is going up in big margin.

As well, all the commodity prices are jumped a lot since 1/2 years ago (in US dollars terms).