21st Century Acquisition Reform and Improvement Act of 2000

21st Century Acquisition Reform and Improvement Act of 2000 - Rewrites provisions of the Clayton Act (the Act) with respect to merger and acquisition notice requirements to limit the circumstances under which notification is required. Requires notification if specified conditions apply, including that, as a result of the acquisition, the acquiring person would hold an aggregate total amount of the voting securities and assets of the acquired person in excess of $200 million, as adjusted and published for the first fiscal year beginning after September 30, 2002, and each third fiscal year thereafter, to reflect the percentage change in the gross national product (GNP) for such fiscal year compared to the GNP for the year ending September 30, 2001, or in excess of $50 million (as so adjusted and published) but not in excess of $200 million (as so adjusted and published).(Sec. 3) Directs the Assistant Attorney General (AAG) and the Federal Trade Commission (FTC) to each designate a senior official who does not have direct responsibility for the review of an enforcement recommendation under the Act concerning the transaction at issue to hear any petition filed by the acquiring person or the person whose voting securities or assets are to be acquired, to determine whether the request for additional information or documentary material is unreasonably cumulative, unduly burdensome, or duplicative, or has been substantially complied with by the petitioning person. Requires that internal review procedures for such petitions include reasonable deadlines for expedited review of such petitions, after reasonable negotiations with investigative staff, in order to avoid undue delay of the merger review process.Directs the AAG and the FTC: (1) within 90 days, to conduct an internal review and implement reforms of the merger review process in order to eliminate unnecessary burden, remove costly duplication, and eliminate undue delay; (2) within 120 days, to issue or amend their respective industry guidance, regulations, operating manuals, and relevant policy documents, where appropriate, to implement each reform in this section; and (3) within 180 days, to each report to Congress which reforms each agency has adopted under this section, which steps each agency has taken to implement internal reforms, and the effects of such reforms.(Sec. 4) Amends the Clayton Act, with respect to calculating filing periods, to: (1) authorize the FTC or AAG to extend the 30-day waiting period for an additional 30 days after receipt of specified information; and (2) direct that if the end of a time period falls on a Saturday, Sunday, or holiday, that such period be extended to the end of the next day that is not a Saturday, Sunday, or holiday.(Sec. 5) Directs the FTC, beginning with the annual report filed in 2001, to include in its report to Congress: (1) the number of notifications filed; (2) the number filed in which the AAG or FTC requested the submission of additional material relevant to the proposed acquisition; (3) data relating to the length of time for parties to comply with such requests; (4) the number of petitions filed and the manner in which they were resolved; (5) data relating to the volume of materials submitted pursuant to such requests; and (6) the number of notifications filed in which such requests were made but never complied with prior to resolution of the case.(Sec. 6) Requires that the thresholds established by rule and promulgated in the Code of Federal Regulations be adjusted by the FTC on January 1, 2003, and each year thereafter, with the adjusted amount rounded to the nearest $1 million. Directs the FTC to publish the adjusted amount by January 31 of each year.