Donald Trump and Conseco Inc., a Carmel, Ind.-based insurer, have bought the General Motors Building in midtown Manhattan. The 50-story landmark, on 5th Avenue across from Central Park between 58th and 59th streets, was sold for $800 million, according to a lawyer who participated in the negotiations. The GM Building was owned for the past 10 years by Corporate Property Investors, a real-estate investment trust that also owns dozens of shopping malls around the U.S. In March, Corporate Property was acquired by Simon DeBartolo Group Inc., the nation's largest mall developer, for $4.9 billion. DeBartolo controls more than 10% of the nation's retail space. Trump, chairman of Trump Hotels & Casino Resorts Inc., also owns Trump Tower and the Trump International Hotel and Tower in Manhattan.