Microsoft said its acquisition of Great Plains Software has cleared the Hart-Scott-Rodino hurdle, allowing the transaction to proceed. Both companies received notice Wednesday from the Federal Trade Commission that the waiting period under the Hart-Scott-Rodino Antitrust Improvement Act has ended. The acquisition, which was announced last December, is expected to close early in Microsoft's fourth quarter. The antitrust act requires an initial waiting period during which parties cannot complete their transaction. At the end of this period, regulators may ask for additional documentation or further information before approving or striking down a merger.