MSN is finding it's in a position to sell holiday ad inventory anywhere from one to two years in advance, reports Mediaweek.

The demand for premium ad placement in the holiday buying season is part of larger movements on a number of fronts.

On the one hand it shows how buyers are trying to bring the same sort of upfront system over to the web from TV, allowing it to make regular and consistent purchases. On the other it shows how those buyers are putting more of the money in the hands of the biggest ad vendors and networks.

Buyers are more comfortable, of course, buying from established players who offer high-quality, safe content.

The trend of buying years — in some cases up to three years — in advance is perpetuated by agencies who want to make sure clients don't let competitors into particularly lucrative spots.

But unlike TV, these upfront style sessions are led by advertisers seeking publishers to meet their needs, not the other way around.