NEW YORK (TheStreet) -- Members of Congress are asking whether college endowments are doing enough to help bring down tuition for college students at a time when student debt is soaring, or whether its helping the richest schools get richer, Bloomberg News' Vonnie Quinn reported on "Bloomberg Market" Wednesday.

More than 40 million Americans currently owe $1.3 trillion in student loans, with more than seven million loans in default.

From the 812 U.S. universities that chose to participate in an industry survey, college endowments totaled to more than $500 billion. About 75% of that was held by the wealthiest 94 universities, each had endowments of $1 billion dollars or more, Quinn said.

Endowments have played an essential role in the rise of some U.S. colleges. In 1932, George Eastman, the inventor and founder of Eastman Kodak, made a $17 million request that turned the University of Rochester into the richest university in the country for several decades.

Endowments have grown as a result of aggressive investment techniques such as private-equity deals, real estate, hedge funds, and commodities. The National Association of College and University Business Officers estimates that 54% of endowments are invested in these and are not liquid.

Today, larger schools with small student population derive half of their operating budgets from endowments, Quinn added.

A congressional research service report estimated taxing college endowment investment income at a 35% rate would have produced $16.2 billion in fiscal 2014. The cost of tax deductions claimed by corporate and individual donors totaled $6.3 billion per year. Both would benefit elite schools, Quinn explained.

An advocacy group estimated that President Barack Obama's need of $6 billion a year to make community college free, could be raised by an excise tax on endowments by 0.5% to 2% for endowments over $500 million.