How Harvard makes so much money — and why a major funding source could be at risk

• Harvard has the biggest endowment in the US, standing at just over $50 billion.
• A chunk of its revenue comes from gifts from alumni, parents, and friends of the school.
• The Education Department's inquiry into the school's legacy admissions process could shake up funding sources.

A major Supreme Court decision put a spotlight on the operations of prestigious colleges, how they admit students, and where their money comes from. And Harvard University recently emerged at the center of that debate.