Ethical question,what would you do and how would you handle it...

Let’s say you found something that if it were to fall in the wrong hands it might leave a nationwide corporation liable in civil lawsuits and if it were sent to the media it would be a complete public relation nightmare for them,costing them money as well the trust of their customers. Would you contact them and inform them of the snafu and leave it at that as you did a good deed or do the preceding but also hint that it would be nice if they reward you for having their backs and hope they do. (criminals would pay handsome for this item) or would you contact the corporation, plainly state what you possess and ask how much is it worth it for them to get this item ?
*Would the latter be considered blackmail ?