London listed Clipper Windpower Plc closed down 10.98% today at 284.43.

Amongst wind companies, Clipper is highly unusual in that it is both a manufacturer at its plant in Iowa and a wind farm developer with 6,000 MW of wind resource rights.

The background to this, according to their annual 2005 accounts is that "When the company was formed in 2001, interest in acquiring wind resource assets in the United States was low" . . . so they did.

This has proved a long-sighted strategy in Britain and Germany, where the number of good wind on land sites have actually become very limited due to planning and resource constraints. This is driving them to look hard at offshore wind power.

However, you do wonder if this is ever going to be a problem in the USA - Clipper's principal market - for a very long time. Growing industries like windpower always specialize and constantly divide effort between emerging specialists.

That's why you wonder how long Clipper's vertically integrated business model will hold into the future.