A new study of Silicon Valley wealth, income and other economic measures shows vast disparities in one of the country's wealthiest regions, with the top 10% of households holding 66% of the investable assets in the region last year. In Santa Clara and San Mateo counties, just eight households held more wealth than the bottom 50% (nearly half a million households), according to the Silicon Valley Index, an annual report by the Silicon Valley Institute for Regional Studies, the research arm of Joint Venture Silicon Valley. | By Alejandro Lazo CalMatters A new study of Silicon Valley wealth, income and other economic measures shows vast disparities in one of the country's wealthiest regions, with the top 10% of households holding 66% of the investable assets in the region last year. In Santa Clara and San Mateo counties, just eight households held more