Collateral Invested Amount means, when used with respect to any date, an amount equal to (a) the Collateral Initial Invested Amount, minus (b) the aggregate amount of principal payments made to the Collateral Interest Holder prior to such date, minus (c) the aggregate amount of Collateral Charge-Offs for all prior Distribution Dates pursuant to subsection 4.06(c), minus (d) the aggregate amount of Reallocated Principal Collections allocated on all prior Distribution Dates pursuant to Section 4.08 allocable to the Collateral Invested Amount, minus (e) an amount equal to the amount by which the Collateral Invested Amount has been reduced on all prior Distribution Dates pursuant to subsections 4.06(a) and (b), and plus (f) the amount allocated and available on all prior Distribution Dates pursuant to subsection 4.07(i), for the purpose of reimbursing amounts deducted pursuant to the foregoing clauses (c), (d) and (e); provided, however, that the Collateral Invested Amount may not be reduced below zero.