Apple Inc AAPL.O shares fell 1%. By Ankika Biswas and Sruthi Shankar May 4 (Reuters) - U.S. stock indexes fell on Thursday after PacWest's move to explore strategic options deepened concerns about the health of regional banks, with uncertainty around the path of U.S. interest rates also weighing on the mood. The Fed on Wednesday raised interest rates by 25 basis points to the 5.00%-5.25% range and signaled a pause in its policy tightening, giving officials time to assess the recent bank failures, U.S. debt ceiling situation and sticky inflation.