definiens: shall mean the period between the date of this LetterAgreement and the date when the earliest of the following shall occur : ( i ) the aggregatenumber of REGN2810 Shares sold pursuant to this Letter Agreement ( including bothREGN2810 Shares to be Purchased and Open - Market REGN2810 Shares ) equals theREGN2810 Share Sale Cap ; ( ii ) if a Purchaser Party does not submit a REGN2810 SaleNotice in respect of the invoice for the last REGN2810 Covered Period, the later of ( x ) thedue date of such invoice and ( y ) the last day of any then - existing REGN2810 SalePeriod ; ( iii ) the end of the REGN2810 Sale Period relating to the lastREGN2810 Covered Period in respect of which a Purchaser Party submits a REGN2810Sale Notice ; and ( iv ) the effective date of termination of the IO LCA pursuant to its terms(including Section 19.7 of the IO LCA )