NEW YORK (Reuters) - Duncan Niederauer, chief executive of NYSE Euronext , said on Friday that Nasdaq OMX's mishandling of Facebook's initial public offering last month "eroded investor confidence" in the short run. "This has clearly eroded investor confidence, the way it was handled," he told CNBC television. Niederauer said it was an unfortunate series of events, and that mistakes are going to happen. "It's how you stand up in the wake of that," he said, referring to Nasdaq's handling of the Facebook IPO. (Edited by Walden Siew) read more..