with borrowings from Ping An Group and interest paid to Ping An Group for its subscription in the consolidated wealth management products managed by us, representing 2.2%, 2.9%, 0.5% and 0.5% of our total expenses for the years ended December 31, 2017, 2018 and 2019 and the six months ended June 30, 2020, respectively.
We had cash balances of RMB18.8 billion, RMB17.5 billion, RMB14.6 billion (US$2.1 billion) and RMB13.2 billion (US$1.9 billion) held at banks who are affiliates with Ping An Group as of December 31, 2017, 2018 and 2019 and June 30, 2020, respectively, representing 10.4%, 14.8%, 9.8% and 6.9% of our total assets as of December 31, 2017, 2018 and 2019 and June 30, 2020, respectively.
We had account and other receivables and contract assets due from Ping An Group in the amount of RMB8,346.0 million, RMB2,606.6 million, RMB2,784.8 million (US$394.2 million) and RMB2,243.7 million (US$317.6 million) as of December 31, 2017, 2018 and 2019 and June 30, 2020, respectively, representing 4.6%, 2.2%, 1.9% and 1.2% of our total assets as of December 31, 2017, 2018 and 2019 and June 30, 2020, respectively.
As of December 31, 2017, 2018 and 2019 and June 30, 2020, we had balance of financial assets at amortized cost and financial investments (loans and receivables) with Ping An Group in the amount of RMB7,546.2 million, RMB1,497.9 million, RMB6,903.3 million (US$977.1 million) and RMB5,902.4 million (US$835.4 million), respectively, primarily in connection with certain asset management plan products we purchased from Ping An Group, representing 4.2%, 1.3%, 4.6% and 3.1% of our total assets as of December 31, 2017, 2018 and 2019 and June 30, 2020, respectively.
As of December 31, 2017, 2018 and 2019 and June 30, 2020, in addition to the convertible promissory notes we issued to PAOH as described below, we had borrowings due to Ping An Group in the amount of RMB12,355.5 million, RMB2,334.6 million, nil and nil, respectively, representing 7.8%, 2.8%, nil and nil of our total liabilities as of December 31, 2017, 2018 and 2019 and June 30, 2020, respectively. The interest rates for these borrowings ranged from 3.0% to 8.2%.
As of December 31, 2017, 2018 and 2019 and June 30, 2020, we had account and other payables and contract liabilities due to Ping An Group in the amount of RMB2,165.0 million, RMB4,018.7 million, RMB2,521.4 million (US$356.9 million) and RMB462.5 million (US$65.5 million), respectively, representing 1.4%, 4.8%, 2.5% and 0.3% of our total liabilities as of December 31, 2017, 2018 and 2019 and June 30, 2020, respectively.
Convertible Promissory Notes Issued to China Ping An Insurance Overseas (Holdings) Limited and An Ke Technology Company Limited
In October 2015, in connection with our acquisition of the retail credit facilitation business from Ping An Group, we issued convertible promissory notes in an aggregate principal amount of US$1,953,800,000, or the Notes, to China Ping An Insurance Overseas (Holdings) Limited, or PAOH. The acquisition was consummated in May 2016. On the same date, PAOH agreed to transfer US$937,824,000 of the outstanding principal amount of the Notes and all rights, benefits and interests attached thereunder to An Ke Technology Company Limited, or An Ke.
Each of the Notes bears interest from the date of issuance, unless otherwise agreed, at the rate of 0.7375% per annum of the principal amount of each of the Notes outstanding from time to time, which will be payable by us semi-annually until the eighth anniversary of the issuance date of the Notes, or the Maturity Date. Subject to the terms and conditions set forth in each of the Notes, each of PAOH and An Ke has the right in the manner provided in the Notes, as applicable, to convert the whole or any part of the outstanding principal amount of the Notes, as applicable, into our Class A ordinary shares, par value US$0.00001 per share (or its equivalent upon the initial public offering of the shares on the stock exchange, including any American depositary shares representing our ordinary shares), during the period starting from the date which is one year after our listing date
262