We determined that none of our leases contained an implicit interest rate and used a discount rate equal to our incremental borrowing rate on a collateralized basis to determine the present value of our total lease payments. As such, we determined the applicable discount rate for each of our leases using a swap rate plus an applicable spread for borrowing arrangements secured by our real estate loans and securities for a length of time equal to the remaining lease term on the date of adoption. At September 30, 2020, the weighted-average remaining lease term and weighted-average discount rate for our leases was 7 years and 5.0%, respectively.

As of September 30, 2020, we had commitments to fund up to $225 million of additional advances on existing residential bridge loans. These commitments are generally subject to loan agreements with covenants regarding the financial performance of the customer and other terms regarding advances that must be met before we fund the commitment. At September 30, 2020, we recorded a $1 million derivative liability related to these commitments to fund construction advances (see Note 7 for additional detail). We may also advance funds related to loans sold under a separate loan sale agreement that are generally repaid immediately by the loan purchaser and do not generally expose us to loss. The outstanding commitments related to these loans that we may temporarily fund totaled approximately $15 million at September 30, 2020.

In the fourth quarter of 2018, we invested in two partnerships created to acquire and manage certain mortgage servicing related assets (see Note 10 for additional detail). In connection with this investment, we are required to fund future net servicer advances related to the underlying mortgage loans. The actual amount of net servicer advances we may fund in the future is subject to significant uncertainty and will be based on the credit and prepayment performance of the underlying loans.

As part of the consideration for our acquisition of 5 Arches, we were committed to make earn-out payments up to $29 million, payable in a mix of cash and Redwood common stock. These contingent earn-out payments were classified as a contingent consideration liability and carried at fair value prior to March 31, 2020. During the first quarter of 2020, we made a cash payment of $11 million and granted $3 million of Redwood common stock in connection with the first anniversary of the purchase date. Additionally, as a result of an amendment to the agreement, we reclassified the contingent liability to a deferred liability, as the remaining payments became payable on a set timetable without any remaining contingencies. At September 30, 2020, the balance of this liability was $14 million, which will be paid in a mix of cash and common stock in March 2021.

In the third quarter of 2019, we entered into a flow purchase agreement to acquire shared home appreciation options. The counterparty purchases an option to buy a fractional interest in a homeowner's ownership interest in residential property, and subsequently the counterparty sells the option contract to us. Pursuant to the terms of the option contract, we share in both home price appreciation and depreciation. At September 30, 2020, we had acquired $47 million of shared home appreciation options under this agreement, which are included in Other investments on our consolidated balance sheets. At September 30, 2020, we had an outstanding commitment to fund up to an additional $3 million under this agreement.

During 2015 and 2016, we sold conforming loans to the Agencies with an original unpaid principal balance of $3.19 billion, subject to our risk-sharing arrangements with the Agencies. At September 30, 2020, the maximum potential amount of future payments we could be required to make under these arrangements was $44 million and this amount was fully collateralized by assets we transferred to pledged accounts and is presented as pledged collateral in Other assets on our consolidated balance sheets. We have no recourse to any third parties that would allow us to recover any amounts related to our obligations under the arrangements. At September 30, 2020, we had not incurred any losses under these arrangements. For the three and nine months ended September 30, 2020, other income related to these arrangements was $1 million and $3 million, respectively, and net market valuation losses related to these investments were $0.3 million and $0.9 million, respectively. For the three and nine months ended September 30, 2019, other income related to these arrangements was $1 million and $2 million, respectively, and net market valuation losses related to these investments were $0.1 million and $0.2 million, respectively.

All of the loans in the reference pools subject to these risk-sharing arrangements were originated in 2014 and 2015, and at September 30, 2020, the loans had an unpaid principal balance of $1.12 billion and a weighted average FICO score of 758 (at origination) and LTV ratio of 75% (at origination). At September 30, 2020, $42 million of the loans were 90 days or more delinquent, and none of these loans were in foreclosure. At September 30, 2020, the carrying value of our guarantee obligation was $11 million and included $5 million designated as a non-amortizing credit reserve, which we believe is sufficient to cover current expected losses under these obligations.

Our consolidated balance sheets include assets of special purpose entities ("SPEs") associated with these risk-sharing arrangements (i.e., the "pledged collateral" referred to above) that can only be used to settle obligations of these SPEs for which the creditors of these SPEs (the Agencies) do not have recourse to Redwood Trust, Inc. or its affiliates. At September 30, 2020 and December 31, 2019, assets of such SPEs totaled $47 million and $48 million, respectively, and liabilities of such SPEs totaled $11 million and $14 million, respectively.

We maintain a repurchase reserve for potential obligations arising from representation and warranty violations related to residential loans we have sold to securitization trusts or third parties and for conforming residential loans associated with MSRs that we have purchased from third parties. We do not originate residential loans and we believe the initial risk of loss due to loan repurchases (i.e., due to a breach of representations and warranties) would generally be a contingency to the companies from whom we acquired the loans. However, in some cases, for example, where loans were acquired from companies that have since become insolvent, repurchase claims may result in our being liable for a repurchase obligation. Additionally, for certain loans we sold during the second quarter of 2020 that were previously held for investment, we have a direct obligation to repurchase these loans in the event of any early payment defaults (or EPDs) by the underlying mortgage borrowers within certain specified periods following the sales.

We received eight and ten repurchase requests during the nine months ended September 30, 2020 and 2019, respectively, and did not repurchase any loans during either of these periods. During the nine months ended September 30, 2020 and 2019, we recorded repurchase provisions of $4 million and reversals of repurchase provisions of $0.2 million, respectively, that were recorded in Mortgage banking activities, net; Investment fair value changes, net; and Other income on our consolidated statements of income (loss).

There is no significant update regarding the litigation matters described in Note 16 within the financial statements included in Redwood’s Annual Report on Form 10-K for the year ended December 31, 2019 under the heading “Loss Contingencies - Litigation.” At September 30, 2020, the aggregate amount of loss contingency reserves established in respect of the FHLB-Seattle and Schwab litigation matters described in our Annual Report on Form 10-K for the year ended December 31, 2019 was $2 million.

In addition to those matters, as previously disclosed, in connection with the impact of the effects of the pandemic on the non-Agency mortgage finance market and on our business and operations, a number of the counterparties that have regularly sold residential mortgage loans to us believe that we breached perceived obligations to them, and requested or demanded that we purchase loans from them and/or compensate them for perceived damages resulting from our decisions earlier in 2020 not to purchase certain loans from them (“Residential Loan Seller Demands”).

We believe that these Residential Loan Seller Demands are without merit or subject to defenses and we intend to defend vigorously any such allegations and any related demand or claim to which we are or become a party. Despite our beliefs about the legal merits of these allegations, because our ordinary course of business is to seek to continue to regularly engage in mutually beneficial transactions with these counterparties, in some cases we have been willing to engage in discussions with these counterparties with the intention of reaching resolution, including through structuring arrangements that incentivize both the counterparty and us to continue to engage in residential loan purchase and sale transactions in the future.

With respect to certain of the Residential Loan Seller Demands, these resolution discussions have been successful in resolving, or establishing a framework that we believe will be the basis for successfully resolving, the demands of these counterparties, including through forward-looking joint business undertakings and structured arrangements that incentivize both the counterparty and us to continue to engage in residential loan purchase and sale transactions in the future. With respect to these counterparties, we have incurred or expect to incur certain costs in connection with finalizing these arrangements (including costs that are contingent on the successful completion of future residential loan purchase and sale transactions with these counterparties that we expect to generate future revenue for the Company) and have recorded any such actual costs incurred through September 30, 2020, as well as an accrual for the estimated costs associated with counterparties where a resolution or go-forward framework has been agreed to or has been discussed but not finalized, a portion of which was recorded through Other expense and a portion of which was recorded through Mortgage banking activities, net on our consolidated income statement. In accordance with GAAP, the accrual for estimated costs is based on the opinion of management, that it is probable that these resolutions and forward-looking joint business undertakings and structured arrangements will result in an expense and the amount of expense can be reasonably estimated. In addition, as previously disclosed, one such counterparty filed a breach of contract lawsuit against us in May 2020 alleging that it had suffered in excess of $2 million of losses as a result of our alleged failure to purchase residential mortgage loans from it; and in October 2020 we and the plaintiff agreed to settle the lawsuit on mutually satisfactory terms.

During the three and nine months ended September 30, 2020, we recorded $4 million and $9 million of expenses, respectively, in association with Residential Loan Seller Demands. At September 30, 2020, the aggregate amount of our accrual for estimated costs associated with Residential Loan Seller Demands was $6.5 million, a portion of which would be contingent on the successful completion of future residential loan purchase and sale transactions with certain counterparties, with the expectation of generating future revenue for the Company.

With respect to Residential Loan Seller Demands that have not been resolved or been accrued for, our beliefs about the legal merits of these allegations and our discussions with these counterparties have resulted in us determining that a significant loss from these matters is not probable. With respect to these remaining Residential Loan Seller Demands, based on the foregoing, we have concluded that we can estimate an aggregate range of reasonably possible losses with respect to these Residential Loan Seller Demands of between zero and $1.5 million.

Future developments (including receipt of additional information and documents relating to these matters, new or additional resolution or settlement communications relating to these matters, resolutions of similar claims against other industry participants in similar circumstances, or receipt of additional Residential Loan Seller Demands) could result in our concluding in the future to establish additional accruals or reserves or modify our aggregate range of reasonably possible losses with respect to these Residential Loan Seller Demand matters. Our actual losses, and any accruals or reserves we may establish in the future relating to these matters, may be materially higher than the accruals, reserves and the aggregate range of reasonably possible losses we have estimated above, respectively, including in the event that any of these matters proceed to trial and result in a judgment against us. We cannot be certain that any of these matters that are not already formally resolved will be resolved through a resolution or settlement and we cannot be certain that the resolution of these matters, whether through litigation, settlement, or otherwise, will not have a material adverse effect on our financial condition or results of operations in any future period.

In accordance with GAAP, we review the need for any loss contingency reserves and establish reserves when, in the opinion of management, it is probable that a matter would result in a liability and the amount of loss, if any, can be reasonably estimated. Additionally, we record receivables for insurance recoveries relating to litigation-related losses and expenses if and when such amounts are covered by insurance and recovery of such losses or expenses are due. We review our litigation matters each quarter to assess these loss contingency reserves and make adjustments in these reserves, upwards or downwards, as appropriate, in accordance with GAAP based on our review.

In the ordinary course of any litigation matter, including certain of the above-referenced matters, we have engaged and may continue to engage in formal or informal settlement communications with the plaintiffs or co-defendants. Settlement communications we have engaged in relating to certain of the above-referenced litigation matters are one of the factors that have resulted in our determination to establish the loss contingency reserves described above. We cannot be certain that any of these matters will be resolved through a settlement prior to litigation and we cannot be certain that the resolution of these matters, whether through trial or settlement, will not have a material adverse effect on our financial condition or results of operations in any future period.