Story highlights Trump hasn't made personal contributions to his foundation since 2008

It appears to have functioned as a conduit that disburses money from third parties

(CNN) On the campaign trail, Donald Trump has touted his political contributions as a form of business savviness, boasting that he has "given to everybody" for favors in return.

But when it comes to his own charity -- The Donald J. Trump Foundation -- the Republican presidential nominee has not donated any money since his last contribution in 2008.

A review of the Trump Foundation's tax records by CNN finds that although the charity has received more than $4 million in contributions from other organizations and individuals and in turn donated millions to various charitable causes since 2009, Trump has not made any personal contributions to the foundation in that time.

The charity appears to have functioned in recent years as a conduit that disburses money donated by third-parties, such as World Wrestling Entertainment, which donated $1 million in 2009, and $500,000 in 2012 from NBC Universal, the company that contracted Trump's show "The Apprentice."

Philanthropy experts describe the practice as irregular since private family foundations traditionally fund charitable causes at least in part through their founder's personal wealth.

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