Nokia Corp. (NOK) has been in and out of the red in choppy trade this morning after Moody’s Investors Service downgraded the company's senior ratings to "A3" from "A2," with a negative outlook. The company's American depositary shares hit a high of $9.09 before turning lower. Shares are now down fractionally at $8.98. Moody's cited weakness in its core business of mobile devices. The ratings, still investment grade, apply to about 5.3 billion euros ($7.6 billion) of debt. Moody's said Nokia's inflexible smart phone operating system, slowness in putting out new models and more attractive innovation by competitors is putting it at a disadvantage.