Apple Inc. began taking orders at 12 a.m. Pacific time Friday (0700 GMT), promising delivery by next Friday, when the new phone also goes on sale in some stores worldwide.
Four hours later, the expected delivery time had grown to two weeks, according to Topeka Capital Markets analyst Brian White.
White said the quick rise suggests much stronger demand than Apple expected. Last year, one-week delivery of the iPhone 4S was available into the afternoon of the first order day.
"Clearly, iPhone 5 fever is in full swing," White said.
Apple's stock rose $8.02, or 1.2 per cent, to $691 in afternoon trading, after hitting an all-time high of $696.98 earlier in the day.