Kmart's ( KMRT) plan to acquire Sears ( S) picked up momentum Friday after the deal cleared the Justice Department's antitrust waiting period. The waiting period prescribed by the Hart-Scott-Rodino Antitrust Improvements Act expired at the end of the day Thursday, Kmart and Sears said. Still, shares of Kmart showed volatility in Friday trading, recently down 28 cents, or 0.3%, to $94.07. Earlier the stock was as high as $95.73, up 1.5%. Shares of Sears were recently up 6 cents, or 0.1%, to $50.14. The waiting period is required to allow the Federal Trade Commission and Department of Justice time to examine any anticompetitive implications of mergers and acquisitions. Antitrust problems were never a major concern regarding this deal on Wall Street, given the significant competitive pressure the company will face. However, regulators did ask the companies to resubmit their regulatory filing in late December to allow for more time to study the plan. The move was blamed on holiday vacations, but some investors questioned whether regulators were giving the deal extra scrutiny since hedge fund guru Ed Lampert with ESL Investments had a controlling stake in both companies prior to the announcement. Also, Kmart had sold a portion of its real estate holdings to Sears at prices that were significantly higher than the valuations given to the assets in Kmart's bankruptcy proceedings in 2003. Shares of Kmart have lost 6% so far in January, while Sears is down more than 3%. First announced in November, the $10.5 billion acquisition is expected to close in early March, after receiving approval from shareholders. It will create the third-largest discount retailing giant, behind Wal-Mart ( WMT) and Target ( TGT). It will be called Sears Holding, and Lampert will act as the company's chairman.