(Wired) Wall Street is buzzing about Apple issuing around $17 billion in bonds. What this means in simple terms is that Apple is borrowing billions of dollars, and paying out a small yield to the people and institutions that purchase the bonds Apple is offering.

This, of course, is the same tech company that is sitting on almost $150 billion in cash. So why would Apple borrow the money, when it already has so much of it sloshing around?

Apple CFO Peter Oppenheimer spelled it out during Apple’s recent earnings call. “We are continuing to generate significant cash offshore,” Oppenheimer told press and analysts. “And repatriating this cash would result in significant tax consequences under current U.S. tax law.” What he didn’t quite spell out was how significant those consequences are.

“Whopping,” is how Jennifer Blouin, associate professor of accounting at the Wharton School, describes it.

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