The benefit (charge) to income, net of tax, as a result of Unlock is as follows:
The Unlock benefit, after tax, for the year ended December 31, 2015 was primarily due to assumption changes related to benefit utilization and lower assumed lapse rates, partially offset by a lower assumed general account spread and higher assumed withdrawal rates.
The Company also utilizes a variety of derivative instruments to mitigate interest rate risk associated with its investment portfolio or to hedge liabilities. Interest rate caps, floors, swaps, swaptions, and futures may be used to manage portfolio duration. Interest rate swaps are primarily used to convert interest receipts or payments to a fixed or variable rate. The use of such swaps enables the Company to customize contract terms and conditions to desired objectives and manage the duration profile within established tolerances. Interest rate swaps are also used to hedge the variability in the cash flow of a forecasted purchase or sale of fixed rate securities due to changes in interest rates. As of December 31, 2016 and 2015, notional amounts pertaining to derivatives utilized to manage interest rate risk, including offsetting positions, totaled $4.6 billion and $6.5 billion, respectively ($4.5 billion and $6.4 billion, respectively, related to investments and $100 and $100, respectively, related to liabilities). The fair value of these derivatives was $(404) and $(377) as of December 31, 2016 and 2015, respectively. These amounts do not include derivatives associated with the Variable Annuity Hedging Program.
The following table presents our estimates of the potential instantaneous impacts from sudden market stresses related to equity market prices, interest rates, and implied market volatilities. The following sensitivities represent: (1) the net estimated difference between the change in the fair value of GMWB liabilities and the underlying hedge instruments and (2) the estimated change in fair value of the hedge instruments for the macro program, before the impacts of amortization of DAC, and taxes. As noted in the preceding discussion, certain hedge assets are used to hedge liabilities that are not carried at fair value and will not have a liability offset in the U.S. GAAP sensitivity analysis. All sensitivities are measured as of December 31, 2016 and are related to the fair value of liabilities and hedge instruments in place at that date for the Company’s variable annuity hedge programs. The impacts presented in the table that follows are estimated individually and measured without consideration of any correlation among market risk factors.
For the company's derivative programs, the maximum uncollateralized threshold for a derivative counterparty for a single legal entity is $10. The Company currently transacts OTC derivatives in two legal entities that have a threshold greater than zero. The maximum combined threshold for a single counterparty across all legal entities that use derivatives is $20. In addition, the Company may have exposure to multiple counterparties in a single corporate family due to a common credit support provider; however, the thresholds for these relationships are zero. Based on the contractual terms of the collateral agreements, these thresholds may be immediately reduced due to a downgrade in either party’s credit rating. For further discussion, see the Derivative Commitments section of Note 10 - Commitments and Contingencies of Notes to Consolidated Financial Statements.
For further information on credit derivatives, see Note 4- Derivative Instruments of Notes to Consolidated Financial Statements.
The Company's investment in the financial services sector decreased, as compared to December 31, 2015, primarily due to sales of corporate securities.
The following table presents the Company’s exposure to CMBS bonds by current credit quality and vintage year included in the preceding Securities by Type table. Credit protection represents the current weighted average percentage of the outstanding capital structure subordinated to the Company’s investment holding that is available to absorb losses before the security incurs the first dollar loss of principal and excludes any equity interest or property value in excess of outstanding debt.
Total general account contractholder obligations are supported by $32 billion of cash and total general account invested assets to meet liquidity needs. As of December 31, 2016, the Company's fixed maturities, short-term investments, and cash are summarized as follows:
Includes consumer notes of $21. Consumer notes include principal payments, contractual interest for fixed rate notes, and interest based on current rates for floating rate notes.