Megaupload.com, a file-sharing website, was shut down as part of an alleged $175 million copyright infringement conspiracy. The action triggered an online protest by the hacker-activist group known as Anonymous that disrupted websites of the US Justice Department and movie and music trade groups. Charges against seven individuals, Megaupload Ltd. and Vestor Ltd. were unsealed yesterday in federal court in Alexandria, Virginia, after four of the alleged conspirators were arrested in Auckland, New Zealand. Three suspects remain at large.