This is interesting, from the AP:
The newly released financial files on Bill and Hillary Rodham Clinton’s growing fortune omit a company with no apparent employees or assets that the former president has legally used to provide consulting and other services, but which demonstrates the complexity of the family’s finances.
And further down:
Under federal ethics disclosure rules, declared candidates do not have to report assets worth less than $1,000. But the company’s existence demonstrates the complexity of tracking the Clintons’ finances as Hillary Clinton ramps up her presidential bid.
While Bill Clinton’s lucrative speeches have provided the bulk of the couple’s income, earning as much as $50 million during his wife’s four-year term as secretary of state in the Obama administration, the former president has also sought to branch out into other business activities in recent years. Little is known about the exact nature and financial worth of Bill Clinton’s non-speech business interests.