daz-
The fact that Stansted has to be sold is not the reason why airlines are not moving there, or starting operations there. It is in BAA's interests for STN to be as busy as possible to enhance its value.
No, the problem is much more fundamental than that. Stansted is not the airlines' first choice of London airport. In fact, it could be the fifth or sixth choice.
Heathrow would be first choice for many, but is slot restricted and very expensive.
Gatwick is now a competitor with capacity, but not cheap. It is closer to affluent catchment areas than STN.
London City is closest to the City and very close to an affluent client base but is slot restricted, expensive and closed part of Saturday/Sunday.
Luton is better connected, has a far larger catchment population, but is congested at certain times.
Southend and Manston are cheaper, but distant from the capital.
At present there is surplus capacity in the south-east of England due to the recession and reduction in air travel, and the least attractive airport is suffering a loss of business as a result. Things will improve for Stansted when the other main competitors fill up, and traffic needs somewhere to go.
Don't forget that most of Stansted's business gains in the '90s and noughties were due to cross-subsidy and the fact that more attractive airports were full.