Passage: Rinehart was Australia's wealthiest person from 2011 to 2015, according to both Forbes and the Financial Review Rich List. Her wealth peaked at around A$29 billion (US$18 billion) in 2012, at which point she overtook Christy Walton as the world's richest woman and was included on the Forbes list of The World's 100 Most Powerful Women. Rinehart's net worth dropped significantly over the following few years, due to a slowdown in the Australian mining sector, but her fortune remains immense.

Question: Who was the second richest Woman in 2012?
Christy Walton