Bloomberg $36.5b [1]
Trump $4.5b [2]
Clinton (household) $111m [3]
Bush $21m [4]
Context: https://en.wikipedia.org/wiki/List_of_United_States_Presiden...
Sources:
[1] http://www.forbes.com/profile/michael-bloomberg
[2] http://www.forbes.com/profile/donald-trump