Fortune down $200 million in past 6 months as certain real estate markets trend downward. Still up $400 million since last year's Forbes 400. As U. of Santa Clara student, began career selling residential property; later segued into commercial real estate. Today Sobrato Development owns and manages 7.7 million square feet of commercial office space, 7,400 residential units, 350 vacant acres in Silicon Valley. Took advantage of growing tech companies' demand for prime real estate; collected higher rents. Biggest clients: Apple and Yahoo. Revitalizing portfolio with newer buildings. Recently bought 245-unit condo tower in Portland, Ore. for $115.5 million. Family foundation gives to nonprofits; recently unveiled Sobrato House Youth Center in San Jose.