Bank of America Corp., the biggest U.S. lender, has made a preliminary offer to bond insurer MBIA Inc. aimed at settling a legal dispute tied to defective mortgages, according to two people briefed on the discussions. The two companies remain split on how much the Charlotte, North Carolina-based bank would have to pay to resolve the disagreement and it is unclear when an agreement can be reached, said the people, who declined to be identified because the talks are private. Bill Halldin, a spokesman for Bank of America, and Kevin Brown of Armonk, New York-based MBIA declined to comment.