A vertical monopoly is where a single company owns, or has control over, the resources required for all stages of production -- all the way up to distribution to the consumer.

For example, if a single company owns or controls foresting, paper manufacture, typesetting and publishing, and book retail processes, that company would be said to have a vertical monopoly in books.

It is quite difficult to achieve a vertcial monopoly, but vertical integration and vertical mergers are very common these days.

Compare: Horizontal Monopoly, Horizontal Merger, Horizontal Integration.

I am not entirely sure on the details and couldn't find any detailed information so feel free to correct me.