Apple Inc. (AAPL) has issued a software update that creates problems for iPhones modified to work with a cellular carrier other than AT&T Inc. (T). Apple warned that the iPhone update — which adds access to the iTunes Wi-Fi Music Store and fixes some security flaws — could permanently disable phones running programs that untether the device from Apple’s exclusive partner network.

UAW-GM contract

Union leaders endorsed a tentative agreement between General Motors Corp. (GM) and the United Auto Workers that requires GM to pay out at least $35 billion for retiree health care and offers an unprecedented number of promises for future work at U.S. plants, according to a summary of the agreement. UAW President Ron Gettelfinger said he’s confident members will support it.