why, page-8

Complex,

In addition to what you suggest. It has been said here for some time that BP and Shell need to improve their reserves. So a move by ENI might also entice the big boys into The Arena to snap up other mid cap oilers.

That also has to be taken into account as to why they all rose at the same time. It is now becoming easier to buy reserves than discover new large oil fields as means of growing your company short to medium term

regards

Acamas