Convertible Notes

At September 30, 2017 and December 31, 2016, the Company's convertible notes payable, net, balance was as follows:



	September 30, 2017		December 31, 2016
Face amount	$	—	$	15,000
Front end fees	—		(75		)
Debt issuance costs	—		(44		)
Back end fees	—		375
Convertible notes payable, net	$	—	$	15,256

On September 30, 2015, the Company entered into a Senior Secured Convertible Note Purchase Agreement (Notes) with various existing stockholders. The Notes provided the Company with up to $30,000 in capital available in two separate tranches. The first tranche of $15,000 closed on September 30, 2015. The second tranche of up to $15,000 was available to the Company until March 30, 2017 but was never drawn. The Notes bore an annual interest rate of 17% and were scheduled to mature on September 30, 2020 if not otherwise converted to Series C-2 shares. The Notes also bore front-end fees of $450, which were paid at issuance, and back end fees of $450 plus interest that was to be paid at maturity. The Notes could be repaid at any time in $100 increments, did not contain any prepayment penalties and were secured by assets of the Company. and OptiNose US, Inc. At the option of the majority purchaser of the Notes after March 30, 2017, or prior to March 30, 2017 if an event of default occurred or was continuing under the Notes, all note principal along with any accrued interest and back end fees thereon, could be converted into Series C-2 shares of preferred stock at a conversion price based upon a Company valuation equal to the lower of fair market value or $300,000.

As of December 31, 2016, the fair value of the Notes was $21,814, which was estimated based on the as converted value of the Notes as of that date.

On March 24, 2017, in connection with the Series D Financing, the Notes and associated accrued interest and back end fees thereon totaling $19,527 converted into 687,474 shares of Series C-2 preferred stock at a per share conversion price of approximately $28.40.

The Company recorded $885 in interest expense during the three months ended September 30, 2016 and $885 and $2,632 during the nine months ended September 30, 2017 and 2016, respectively, in conjunction with the Notes. Total coupon interest on the Notes and back end fees was $743 and $2,275 during the nine months ended September 30, 2017 and 2016, respectively. The front-end fees of $450 were recorded as debt discount at issuance and were amortized to interest expense over the 18 month loan conversion period. During the three months ended September 30, 2016 and for the nine month periods ended September 30, 2017 and 2016, the Company recorded a total of $75, $75, and $225 of interest expense, respectively, related to the front end fees. Additionally, back end fees of $450 are also being amortized to interest expense over the 18 month loan conversion period of which $95, $90, and $285 has been recorded as interest expense and as an increase in the carrying amount of the Notes during the three months ended September 30, 2016 and the nine months ended September 30, 2017 and 2016, respectively. The Company also incurred $265 in debt issuance costs during the year ended December 31, 2015 which are also being amortized to interest expense over the 18 month loan conversion period.