Apple Inc. suffered its third consecutive daily drop, closing below $500 — something it hasn’t done in almost a year. On Monday, Apple fell 3.6 percent. The concern is that demand for the iPhone 5 is slowing. The Nikkei newswire said orders for iPhone 5 parts have been cut 50 percent due to slow sales. Shares of Sharp and other suppliers to Apple also declined. Yet, Barclays analyst Jones Ku said, ‘‘The actual order­ cut for iPhone 5s in the first quarter is exaggerated.’’