RELATED PARTY BALANCES AND TRANSACTIONS	9 Months Ended
Sep. 30, 2019
RELATED PARTY BALANCES AND TRANSACTIONS [Abstract]
RELATED PARTY BALANCES AND TRANSACTIONS	NOTE 11– RELATED PARTY BALANCES AND TRANSACTIONS On August 18, 2017, ACM and Ninebell, its equity method investment affiliate (note 10), entered into a loan agreement pursuant to which ACM made an interest-free loan of $946 to Ninebell, payable in 180 days or automatically extended another 180 days if in default. The loan was secured by a pledge of Ninebell’s accounts receivable due from ACM and all money that Ninebell received from ACM. Ninebell repaid the loan in March 2018. ACM purchased materials from Ninebell amounting to $2,591 and $2,529 during the three months ended September 30, 2019 and 2018, and $7,395 and $5,364 during the nine months ended September 30, 2019 and 2018, respectively. As of September 30, 2019 and December 31, 2018, accounts payable due to Ninebell were $809 and $1,477, respectively, and prepaid expenses prepaid to Ninebell for material purchases were $160 and $572, respectively. ACM purchased materials from Shengyi amounting to $261 and $453 during the three and nine months ended September 30, 2019, respectively. As of September 30, 2019, accounts payable due to Shengyi was $496. In 2007 ACM Shanghai entered into an operating lease agreement with Shanghai Zhangjiang Group Co., Ltd. (“Zhangjiang Group”) to lease manufacturing and office space located in Shanghai, China. An affiliate of Zhangjiang Group holds 787,098 shares of Class A common stock that it acquired in September 2017 for $5,903. Pursuant to the lease agreement, Zhangjiang Group provided $771 to ACM Shanghai for leasehold improvements. In September 2016 the lease agreement was amended to modify payment terms and extend the lease through December 31, 2017. From January 1 to April 25, 2018, ACM Shanghai leased the property on a month-to-month basis. On April 26, 2018, ACM Shanghai entered into a renewed lease with Zhangjiang Group for the period from January 1, 2018 through December 31, 2022. Under the lease, ACM Shanghai pays a monthly rental fee of RMB 366 (equivalent to $55). The required security deposit was RMB 1,077 (equivalent to $163). The Company incurred leasing expenses under the lease agreement of $148 and $152 during the three months ended September 30, 2019 and 2018, respectively, and $448 and $471 during the nine months ended September 30, 2019 and 2018, respectively. As of September 30, 2019 and December 31, 2018, payables to Zhangjiang Group for lease expenses and leasehold improvements recorded as other payables and accrued expenses amounted to $0 and $53, respectively (note 7). On December 9, 2016, Shengxin (Shanghai) Management Consulting Limited Partnership, a PRC limited partnership owned by Jian Wang (Vice President, Research and Development, and brother of David H. Wang) and other employees of ACM Shanghai (“SMC”), delivered RMB 20,124 ($2,981 as of the close of business on such date) in cash (the “SMC Investment”) to ACM Shanghai for potential investment pursuant to terms to be subsequently negotiated. SMC is a limited partnership incorporated in the PRC, whose partners consist of employees of ACM Shanghai. On March 14, 2017, ACM, ACM Shanghai and SMC entered into a securities purchase agreement (the “SMC Agreement”) pursuant to which, in exchange for the SMC Investment, ACM issued to SMC a warrant (the “SMC Warrant”) exercisable, for cash or on a cashless basis, to purchase, at any time on or before May 17, 2023, all, but not less than all, of 397,502 shares of Class A common stock at a price of $7.50 per share, for a total exercise price of $2,981. On March 30, 2018, SMC exercised the SMC Warrant in full and purchased 397,502 shares of Class A common stock (note 12). On August 14, 2019, ACM entered into an equity purchase agreement (the “Equity Purchase Agreement”) under which it agreed to repurchase, at a price per share of $13.195 (the net proceeds per share ACM received in a public offering of Class A common stock, as described in note 13), shares of Class A common stock from certain directors, employees and SMC upon the exercise of the underwriters’ over-allotment option in connection with the public offering in August 2019. The total consideration to the directors, employees and SMC, in exchange for their surrender of 214,286 shares of Class A common stock and cancellation of 53,571 options to acquire Class A common stock (note 15) amounted to $3,403, which was based at a price of $13.195 per share equal to the net proceeds per share ACM received from the over-allotment option in connection with this offering. Of that total amount, $1,990 due to SMC was recorded in other payable and accrued expenses (note 7).

NOTE 11– RELATED PARTY BALANCES AND TRANSACTIONS

On August 18, 2017, ACM and Ninebell, its equity method investment affiliate (note 10), entered into a loan agreement pursuant to which ACM made an interest-free loan of $946 to Ninebell, payable in 180 days or automatically extended another 180 days if in default. The loan was secured by a pledge of Ninebell’s accounts receivable due from ACM and all money that Ninebell received from ACM. Ninebell repaid the loan in March 2018. ACM purchased materials from Ninebell amounting to $2,591 and $2,529 during the three months ended September 30, 2019 and 2018, and $7,395 and $5,364 during the nine months ended September 30, 2019 and 2018, respectively. As of September 30, 2019 and December 31, 2018, accounts payable due to Ninebell were $809 and $1,477, respectively, and prepaid expenses prepaid to Ninebell for material purchases were $160 and $572, respectively.

ACM purchased materials from Shengyi amounting to $261 and $453 during the three and nine months ended September 30, 2019, respectively. As of September 30, 2019, accounts payable due to Shengyi was $496.

In 2007 ACM Shanghai entered into an operating lease agreement with Shanghai Zhangjiang Group Co., Ltd. (“Zhangjiang Group”) to lease manufacturing and office space located in Shanghai, China. An affiliate of Zhangjiang Group holds 787,098 shares of Class A common stock that it acquired in September 2017 for $5,903. Pursuant to the lease agreement, Zhangjiang Group provided $771 to ACM Shanghai for leasehold improvements. In September 2016 the lease agreement was amended to modify payment terms and extend the lease through December 31, 2017. From January 1 to April 25, 2018, ACM Shanghai leased the property on a month-to-month basis. On April 26, 2018, ACM Shanghai entered into a renewed lease with Zhangjiang Group for the period from January 1, 2018 through December 31, 2022. Under the lease, ACM Shanghai pays a monthly rental fee of RMB 366 (equivalent to $55). The required security deposit was RMB 1,077 (equivalent to $163). The Company incurred leasing expenses under the lease agreement of $148 and $152 during the three months ended September 30, 2019 and 2018, respectively, and $448 and $471 during the nine months ended September 30, 2019 and 2018, respectively. As of September 30, 2019 and December 31, 2018, payables to Zhangjiang Group for lease expenses and leasehold improvements recorded as other payables and accrued expenses amounted to $0 and $53, respectively (note 7).

On December 9, 2016, Shengxin (Shanghai) Management Consulting Limited Partnership, a PRC limited partnership owned by Jian Wang (Vice President, Research and Development, and brother of David H. Wang) and other employees of ACM Shanghai (“SMC”), delivered RMB 20,124 ($2,981 as of the close of business on such date) in cash (the “SMC Investment”) to ACM Shanghai for potential investment pursuant to terms to be subsequently negotiated. SMC is a limited partnership incorporated in the PRC, whose partners consist of employees of ACM Shanghai. On March 14, 2017, ACM, ACM Shanghai and SMC entered into a securities purchase agreement (the “SMC Agreement”) pursuant to which, in exchange for the SMC Investment, ACM issued to SMC a warrant (the “SMC Warrant”) exercisable, for cash or on a cashless basis, to purchase, at any time on or before May 17, 2023, all, but not less than all, of 397,502 shares of Class A common stock at a price of $7.50 per share, for a total exercise price of $2,981. On March 30, 2018, SMC exercised the SMC Warrant in full and purchased 397,502 shares of Class A common stock (note 12).

On August 14, 2019, ACM entered into an equity purchase agreement (the “Equity Purchase Agreement”) under which it agreed to repurchase, at a price per share of $13.195 (the net proceeds per share ACM received in a public offering of Class A common stock, as described in note 13), shares of Class A common stock from certain directors, employees and SMC upon the exercise of the underwriters’ over-allotment option in connection with the public offering in August 2019. The total consideration to the directors, employees and SMC, in exchange for their surrender of 214,286 shares of Class A common stock and cancellation of 53,571 options to acquire Class A common stock (note 15) amounted to $3,403, which was based at a price of $13.195 per share equal to the net proceeds per share ACM received from the over-allotment option in connection with this offering. Of that total amount, $1,990 due to SMC was recorded in other payable and accrued expenses (note 7).