Shares of Qualcomm ( QCOM ) are slipping after Bernstein analyst Stacy Rasgon downgraded the stock to Market Perform, citing a lack of confidence in the company's long-term growth and Wall Street estimates that appear to be too high for the quarter. This comes less than a month after reports indicated that Apple's (AAPL) next iPhone will use modems from Intel ( INTC ), replacing Qualcomm's chips in some versions of the smartphone.