Nasdaq OMX Group Inc. ( NDAQ ) is facing a fine from U.S. securities regulators related to the Stock market operator's missteps during last year's debut of Social networking giant Facebook, Inc. (FB), the Wall Street Journal reported Tuesday, citing people with knowledge of the matter. As per the report, the missteps cost Wall Street an estimated $500 million, and the regulators may seek 1% of that from the exchange group as fine. Nasdaq is in preliminary talks with the Securities and Exchange Commission or SEC over a potential settlement related to its botched handling of Facebook's offering. For the past few months, SEC has been investigating Facebook's May 18 IPO. According to people with knowledge of the talks, both sides are discussing a monetary penalty of about $5 million, and Nasdaq has also offered to compensate customers $62 million for losses stemming from Facebook IPO trades.