Shares of other Apple suppliers including Qualcomm QCOM.O, Broadcom AVGO.O, Qorvo QRVO.O and Corning GLW.N fell between 1.2% to 2%. By Shreyashi Sanyal and Shristi Achar A May 9 (Reuters) - U.S. stock indexes fell on Tuesday as investors turned cautious ahead of a key inflation reading this week, while dour earnings forecasts from companies such as PayPal and Apple supplier Skyworks weighed on the mood. Shares of PayPal Holdings PYPL.O dropped 12% and led declines on the benchmark S&P 500 index .SPXafter the company cut its margin forecast.