A debt-free balance sheet with more cash than the combined funds of every AAA-rated U.S. company failed to win Apple Inc. the bond market's highest credit grade as the iPhone maker prepares to borrow to enrich shareholders.

Apple, which has $145 billion of cash, said yesterday it plans to use debt to help finance a $100 billion capital reward for shareholders after a 42 percent stock plunge. Moody's Investors Service and Standard & Poor's responded by ranking the company a level below their top grades, with Gerald Granovsky of Moody's citing "shifting consumer preferences" in a statement as a risk to Cupertino, California-based Apple's business.

The decisions give Apple lower ratings than Microsoft Corp., Johnson & Johnson, Exxon Mobil Corp. and Automatic Data Processing Inc., whose combined debt of $42 billion accounts for about 13 percent of their equity. Apple could borrow more than $17 billion and still maintain a ratio below that, according to data compiled by Bloomberg.