definiens: which is agreed and understood to mean the later of ( 1 ) the execution date of the Development & CommercializationAgreement, ( 2 ) if a determination is made pursuant to this Section 5.9 that a notification of this Agreement is not required tobe made under the HSR Act, the date of such determination, or ( 3 ) if notification of this Agreement is required to be madeunder the HSR Act, the HSR Clearance Date . As used herein : ( x ) means the Hart - Scott - Rodino AntitrustImprovements Act of 1976, as amended, and the rules and regulations promulgated thereunder ; ( y ) means the earliest date on which the Parties have actual knowledge that all applicable waiting periods under the HSR Act withrespect to the transactions contemplated by a Development & Commercialization Agreement have expired or have beenterminated ; and ( z ) means a filing by [COMPANY] and Bluebird with the United States of America Federal TradeCommission and the 27CERTAIN CONFIDENTIAL PORTIONS OF THIS EXHIBIT WERE OMITTED AND REPLACED WITH . ACOMPLETE VERSION OF THIS EXHIBIT HAS BEEN FILED SEPARATELY WITH THE SECRETARY OF THESECURITIES AND EXCHANGE COMMISSION PURSUANT TO AN APPLICATION REQUESTING CONFIDENTIALTREATMENT PURSUANT TO RULE 406 PROMULGATED UNDER THE SECURITIES ACT OF 1933, AS AMENDED