SECURITIES

Regulators Probe Unusual Trades in Uunet Shares: The National Assn. of Securities Dealers and the Chicago Board Options Exchange have launched a joint investigation into unusual trading in advance of the announcement this week that Omaha-based MFS Communications Co. would acquire Fairfax, Va.-based Uunet Technologies Inc., regulatory sources said. Unusually active trading in Uunet shares drove the stock higher just before the deal was announced. The NASD and CBOE surveillance departments want to make sure that traders did not take improper advantage of insider information about the merger, the sources said. If the exchanges’ surveillance departments find evidence of possible wrongdoing, the sources said, they would jointly forward their findings to the Securities and Exchange Commission.