EDISON SCHOOLSSize

74,000 students, 133 schoolsRevenues

$525 million*Status

Fighting to remain afloat, with stock down more than 90% this year. Has lost more than $260 million since 1992.NOBEL LEARNING COMMUNITIESSize

25,000 students, 174 schoolsRevenues

$160 millionStatus

Profitable Nasdaq-listed outfit runs private, charter, and special schools, such as those for the learning-challenged.NATIONAL HERITAGE ACADEMIESSize

14,000 students, 28 schoolsRevenues

$100 million*Status

Private company says it's making money. Its schools stress

uniforms, discipline, parental involvement.MOSAICA EDUCATIONSize

11,000 students, 40 schoolsRevenues

$70 millionStatus

Acquired troubled Advantage Schools last year. Raised more than $100 million from Fidelity, U.S. Trust, others.* Estimated