Manchester United filed for an initial public offering in the United States on Tuesday, a move that would return the English soccer team to the public markets. The club set a preliminary fund-raising target of $100 million to determine registration fees. It had previously hoped to raise about $1 billion in either Hong Kong or Singapore. Manchester United had traded on the London Stock Exchange before Malcolm Glazer, an American who also controls the Tampa Bay Buccaneers football team, took the company private in a $1.45 billion buyout in 2005.