Sears Holdings Corp. formed a joint venture with shopping mall owner Macerich Co., the latest step in the department-store chain's efforts to wring more money from its real estate. The 50-50 venture is taking over nine Sears properties, all of which are within Macerich malls, according to a statement Thursday. As part of the transaction, Macerich contributed $150 million to Sears. The Hoffman Estates, Ill.-based chain will continue to operate the stores involved in the deal. The move is part of a broader effort to raise more than $2.5 billion from Sears’ extensive real estate holdings.