what is this upgrade worth for marenica ???, page-4

A possible source of disappointment could be the COG (cut off grade). They state in the announcement that the COG is 80ppm. Is this consistant with previous announcements? If not (i.e. the cutoff grade used here is lower than the COG used previously), then today's announcement could be viewed (at least partially) as a 'Claytons' upgrade. If it is, then management have a lot to answer for. Also remember that stocks don't react to news per se. It is the difference between what is EXPECTED by the mkt as a whole and the details of the announcement that's important. For example, on face value, a doubling of reserves may sounds wonderful news for a particular mining company. In isolation, one would expect the share price to act favourably if there was a doubling of reserves. However, if the mkt was expecting a tripling of reserves, then the stock in question would get belted. This is a subtle point at first, but a critically important one for investors