$3bn hit for WA's biggest mine moguls ALMOST $3 billion has been wiped off the net worth of some of Perth's most prominent mining executives this year, underscoring the pain being felt at the top end of a West Australian economy that appears to be cooling rapidly. An analysis of data by The Australian has found that the average value of the shareholdings held by 10 of the biggest names in WA's resources-dominated economy has fallen by more than 38 per cent from the peaks of the past six months.