The consolidated financial statements have been prepared in accordance with U.S. generally accepted accounting principles ("U.S. GAAP").

The consolidated financial statements include the financial statements of the Company and its subsidiaries. All intercompany transactions and balances among the Group and its subsidiaries are eliminated upon consolidation.

The preparation of the consolidated financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities, and disclosures of contingent assets and liabilities at the date of the financial statements and the reported amounts of expenses during the period. Areas where management uses subjective judgment include estimating the useful lives of long-lived assets, assessing the impairment of long-lived assets, revenue recognition, valuation of ordinary shares, share-based compensation expenses, recoverability of deferred tax assets and the fair value of the financial instruments. Management bases the estimates on historical experience and various other assumptions that are believed to be reasonable, the results of which form the basis for making judgments about the carrying values of assets and liabilities. Actual results could differ from these estimates.

The functional currency of Zai Lab Limited and Zai Lab (Hong Kong) Limited are the United States dollar ("$"). The Group's PRC subsidiaries determined their functional currency to be Chinese Renminbi ("RMB"). The Group's Australia subsidiary determined its functional currency to be Australia dollar ("A$"). The determination of the respective functional currency is based on the criteria of Accounting Standard Codification ("ASC") 830, Foreign Currency Matters. The Group uses the United States dollar as its reporting currency.

Assets and liabilities are translated from each entity's functional currency to the reporting currency at the exchange rate on the balance sheet date. Equity amounts are translated at historical exchange rates, and expenses, gains and losses are translated using the average rate for the year. Translation adjustments are reported as cumulative translation adjustments and are shown as a separate component of other comprehensive loss in the consolidated statements of changes in shareholders' deficits and comprehensive loss.

Monetary assets and liabilities denominated in currencies other than the applicable functional currencies are translated into the functional currencies at the prevailing rates of exchange at the balance sheet date. Nonmonetary assets and liabilities are remeasured into the applicable functional currencies at historical exchange rates. Transactions in currencies other than the applicable functional currencies during the year are converted into the functional currencies at the applicable rates of exchange prevailing at the transaction dates. Transaction gains and losses are recognized in the consolidated statements of operations.

The Group considers all highly liquid investments purchased with original maturities of three months or less to be cash equivalents. Cash and cash equivalents consist primarily of cash on hand, demand deposits and highly liquid investments with maturity of less than three months and are stated at cost plus interests earned, which approximates fair value.

Short-term investments are time deposits with original maturities more than three months. Short-term investments are stated at cost, which approximates fair value. Interests are included in interest income.

Accounts receivable are recorded at the amounts due from customers and net of allowances for doubtful accounts. An allowance for doubtful accounts is recorded when the collection of the full amount is no longer probable. In evaluating the collectability of accounts receivable, the Group considers many factors including aging of the receivable due, the customer's payment history, creditworthiness, financial conditions, and current economic trends. Credit losses of accounts receivable, which may be for all or part of a particular accounts receivable, shall be deducted from the allowance. The related accounts receivable balance shall be charged off in the period in which the accounts receivable are deemed uncollectible. Recoveries of accounts receivable previously charged written off shall be recorded when received. The Group regularly reviews the adequacy and appropriateness of any allowance for doubtful accounts. No allowance for doubtful accounts was recorded as of December 31, 2018.

Inventories are stated at the lower of cost or net realizable value, with cost determined on a weighted average basis. The Group periodically reviews the composition of inventory in order to identify obsolete, slow-moving or otherwise non-saleable items. The Group will record a write-down to its net realizable value in the period that the decline in value is first identified. No inventory provision was recorded as of December 31, 2018.

The Group uses the equity method to account for an equity investment over which it has significant influence but does not own a majority equity interest or otherwise control. The Group records equity method adjustments in share of earnings and losses. Equity method adjustments include the Group’s proportionate share of investee income or loss, adjustments to recognize certain differences between the Group’s carrying value and its equity in net assets of the investee at the date of investment, impairments, and other adjustments required by the equity method. Dividends received are recorded as a reduction of carrying amount of the investment. Cumulative distributions that do not exceed the Group’s cumulative equity in earnings of the investee are considered as a return on investment and classified as cash inflows from operating activities. Cumulative distributions in excess of the Group’s cumulative equity in the investee’s earnings are considered as a return of investment and classified as cash inflows from investing activities.

For equity investments over which the Group does not have significant influence or control, the cost method of accounting is used. Under the cost method, the Group carries the investment at cost and recognizes income to the extent of dividends received from the distribution of the equity investee’s post-acquisition profits.

The Group is required to perform an impairment assessment of its investments whenever events or changes in business circumstances indicate that the carrying value of the investment may not be fully recoverable. An impairment loss is recorded when there has been a loss in value of the investment that is other than temporary. No impairment was recorded for the years ended December 31, 2016, 2017 and 2018.

The prepayments for equipment purchase are recorded in long term prepayments considering the prepayments are all related to property and equipment.

Property and equipment are stated at cost, less accumulated depreciation and amortization. Depreciation is computed using the straight-line method over the estimated useful lives of the respective assets as follows:

		Useful life
Office equipment		3 years
Electronic equipment		3 years
Vehicle		4 years
Laboratory equipment		5 years
Manufacturing equipment		10 years
Leasehold improvements		lesser of useful life or lease term

Construction in progress represents property and equipment under construction and pending installation and is stated at cost less impairment losses if any.

Long term deposits represent amounts paid in connection with the Group’s long-term lease agreements.

Value added tax recoverable represent amounts paid by the Group for purchases. The amounts were recorded as long-term assets considering they are expected to be deducted from future value added tax payables arising on the Group's revenues which it expects to generate in the future.

Intangible assets mainly consist of externally purchased software which are amortized over one to five years on a straight-line basis. Amortization expenses for the years ended December 31, 2016, 2017 and 2018 were $781, $2,422 and $15,398, respectively. Amortization expenses of the Group's intangible assets are expected to be approximately $206,881, $41,584, $26,562, $24,940 and $21,599 for the years ended December 31, 2019, 2020, 2021, 2022, 2023 and thereafter, respectively.

Long-lived assets are reviewed for impairment in accordance with authoritative guidance for impairment or disposal of long-lived assets. Long-lived assets are reviewed for events or changes in circumstances, which indicate that their carrying value may not be recoverable. Long-lived assets are reported at the lower of carrying amount or fair value less cost to sell. For the years ended December 31, 2016, 2017 and 2018, there was no impairment of the value of the Group's long-lived assets.

The Group applies ASC topic 820 ("ASC 820"), Fair Value Measurements and Disclosures, in measuring fair value. ASC 820 defines fair value, establishes a framework for measuring fair value and requires disclosures to be provided on fair value measurement.

ASC 820 establishes a three-tier fair value hierarchy, which prioritizes the inputs used in measuring fair value as follows:

Level 1 - Observable inputs that reflect quoted prices (unadjusted) for identical assets or liabilities in active markets.

Level 2 - Include other inputs that are directly or indirectly observable in the marketplace.

Level 3 - Unobservable inputs which are supported by little or no market activity.

ASC 820 describes three main approaches to measuring the fair value of assets and liabilities: (1) market approach; (2) income approach and (3) cost approach. The market approach uses prices and other relevant information generated from market transactions involving identical or comparable assets or liabilities. The income approach uses valuation techniques to convert future amounts to a single present value amount. The measurement is based on the value indicated by current market expectations about those future amounts. The cost approach is based on the amount that would currently be required to replace an asset.

Financial instruments of the Group primarily include cash and cash equivalents, short-term investments, accounts receivable, prepayments and other current assets, short-term borrowings, accounts payable and other payables. As of December 31, 2017 and 2018, the carrying values of cash and cash equivalents, short-term investments, accounts receivable, prepayments and other current assets, short-term borrowings, accounts payable and other payable approximated their fair values due to the short-term maturity of these instruments.

In May 2014, the Financial Accounting Standards Board (FASB) issued a comprehensive new standard which amends revenue recognition principles. In 2018, the Group adopted of ASC topic 606 ("ASC 606"), Revenue from Contracts with Customers, in recognition of revenue. Under ASC 606, the Group recognizes revenue when its customer obtains control of promised goods or services, in an amount that reflects the consideration expected to receive in exchange for those goods or services. To determine revenue recognition for arrangements that the Group determines are within the scope of ASC 606, the Group performs the following five steps: (i) identify the contract(s) with a customer; (ii) identify the performance obligations in the contract; (iii) determine the transaction price, including variable consideration, if any; (iv) allocate the transaction price to the performance obligations in the contract; and (v) recognize revenue when (or as) the Group satisfies a performance obligation. The Group only applies the five-step model to contracts when it is probable that the Group will collect the consideration to which it is entitled in exchange for the goods or services it transfers to the customer. Once a contract is determined to be within the scope of ASC 606 at contract inception, the Group reviews the contract to determine which performance obligations it must deliver and which of these performance obligations are distinct. The Group recognizes as revenue the amount of the transaction price that is allocated to each performance obligation when that performance obligation is satisfied or as it is satisfied.

The Group's principal source of revenue is product sales. The contracts with customers generally contain a single performance obligation and the Group recognizes revenue from product sales when the Group has satisfied the performance obligation by transferring control of the product to the customers. Control of the product generally transfers to the customer upon delivery.

The timing between the recognition of revenue for product sales and the receipt of payment is not significant. Therefore the Group do not assess whether a contract has a significant financing component if the expectation at contract inception is such that the period between the transfer of the promised good to the customer and receipt of payment will be one year or less

For the year ended December 31, 2018, the Group's product revenues were generated from the sale of ZEJULA (niraparib) to customers, which are typically healthcare providers such as oncology centers. The Group utilizes a distributor in Hong Kong for warehousing services. Based on the nature of the arrangement, the Group has determined that it is a principal in the transaction since the Group is primarily responsible for fulfilling the promise to provide the products to the customer, maintains inventory risk until delivery to the customer and has latitude in establishing the price. Revenue was recognized at the amount to which the Group expected to be entitled in exchange for the sale of the products, which is the sales price agreed with the customers. Consideration paid to the distributor is recognized in operating expenses.

Elements of research and development expenses primarily include (1) payroll and other related costs of personnel engaged in research and development activities, (2) in-licensed patent rights fee of exclusive development rights of drugs granted to the Group, (3) costs related to preclinical testing of the Group’s technologies under development and clinical trials such as payments to contract research organizations (“CROs”), investigators and clinical trial sites that conduct our clinical studies (4) costs to develop the product candidates, including raw materials and supplies, product testing, depreciation, and facility related expenses, (5) other research and development expenses. Research and development expenses are charged to expense as incurred when these expenditures relate to the Group’s research and development services and have no alternative future uses.

The Group has acquired rights to develop and commercialize product candidates. Upfront payments that relate to the acquisition of a new drug compound, as well as pre-commercial milestone payments, are immediately expensed as acquired in-process research and development in the period in which they are incurred, provided that the new drug compound did not also include processes or activities that would constitute a “business” as defined under US GAAP, the drug has not achieved regulatory approval for marketing and, absent obtaining such approval, has no established alternative future use. Milestone payments made to third parties subsequent to regulatory approval would be capitalized as intangible assets and amortized over the estimated remaining useful life of the related product. The conditions enabling capitalization of development costs as an asset have not yet been met and, therefore, all development expenditures are recognized in profit or loss when incurred.

Deferred income consists of deferred income from government grants and American Depositary Receipts (the "ADR") Program Agreement with ADR depositary bank (the “DB”) in July 2017.

Government grants consist of cash subsidies received by the Group's subsidiaries in the PRC from local governments. Grants received as incentives for conducting business in certain local districts with no performance obligation or other restriction as to the use are recognized when cash is received. Cash grants of $2,065,510, $855,158 and $1,332,419 were included in other income for the years ended December 31, 2016, 2017 and 2018, respectively. Grants received with government specified performance obligations are recognized when all the obligations have been fulfilled. If such obligations are not satisfied, the Group may be required to refund the subsidy. Cash grants of $912,124 and $893,942 were recorded in deferred income as of December 31, 2017 and 2018 respectively, which will be recognized when the government specified performance obligation is satisfied.

According to the ADR program agreement, the Group has the right to receive reimbursements for using DB's services, subject to the compliance by the Group with the terms of the Agreement. The Group performed a detailed assessment of the requirements and recognizes the reimbursements it is expected to be entitled to over the five-year contract term as other income. For the year ended December 31, 2017 and 2018, $78,000 and $312,000 were recorded in other income, respectively, and $1,482,000 and $1,170,000 were recorded in deferred income as of December 31, 2017 and 2018, respectively.

Leases are classified at the inception date as either a capital lease or an operating lease. the Group assesses a lease to be a capital lease if any of the following conditions exist: (1) ownership is transferred to the lessee by the end of the lease term, (2) there is a bargain purchase option, (3) the lease term is at least 75% of the property's estimated remaining economic life or (4) the present value of the minimum lease payments at the beginning of the lease term is 90% or more of the fair value of the leased property to the lessor at the inception date. A capital lease is accounted for as if there was an acquisition of an asset and an incurrence of an obligation at the inception of the lease. The Group has no capital leases for the years presented.

All other leases are accounted for as operating leases wherein rental payments are expensed on a straight-line basis over the periods of their respective lease terms. The Group leases office space and employee accommodation under operating lease agreements. Certain of the lease agreements contain rent holidays. Rent holidays are considered in determining the straight-line rent expense to be recorded over the lease term. The lease term begins on the date of initial possession of the lease property for purposes of recognizing lease expense on straight-line basis over the term of the lease.

Comprehensive loss is defined as the changes in equity of the Group during a period from transactions and other events and circumstances excluding transactions resulting from investments by owners and distributions to owners. Among other disclosures, ASC 220, Comprehensive Income, requires that all items that are required to be recognized under current accounting standards as components of comprehensive loss be reported in a financial statement that is displayed with the same prominence as other financial statements. For each of the periods presented, the Group's comprehensive loss includes net loss and foreign currency translation adjustments, which are presented in the consolidated statements of comprehensive loss.

The Group grants share options to eligible employees, management and directors and accounts for these share based awards in accordance with ASC 718, Compensation-Stock Compensation.

Employees' share-based awards are measured at the grant date fair value of the awards and recognized as expenses (1) immediately at grant date if no vesting conditions are required; or (2) using graded vesting method over the requisite service period, which is the vesting period.

All transactions in which goods or services are received in exchange for equity instruments are accounted for based on the fair value of the consideration received or the fair value of the equity instrument issued, whichever is more reliably measurable.

To the extent the required vesting conditions are not met resulting in the forfeiture of the share-based awards, previously recognized compensation expense relating to those awards are reversed.

The Group determined the fair value of the stock options granted to employees. Before 2018, the Group applied binomial option pricing model in determining the estimated fair value of the options granted to employees. In 2018, the Group changed to use the Black-Scholes option valuation model since the Group expected the Black-Scholes option valuation model provide a better estimate of fair value. A change in the valuation technique is a change in accounting estimate for the purposes of applying ASC 250, and shall be applied prospectively to new awards.

The Group has accounted for equity instruments issued to non-employees in accordance with the provisions of ASC 505, Equity-Based Payments to Non-Employees. All transactions in which goods or services are received in exchange for equity instruments are accounted for based on the fair value of the consideration received or the fair value of the equity instrument issued, whichever is more reliably measurable. The measurement date of the fair value of the equity instrument issued is the date on which the counterparty's performance is completed as there is no associated performance commitment. The expense is recognized in the same manner as if the Group had paid cash for the services provided by the non-employees in accordance with ASC 505.

Income tax expense includes (a) deferred tax expense, which generally represents the net change in the deferred tax asset or liability balance during the year plus any change in valuation allowances; (b) current tax expense, which represents the amount of tax currently payable to or receivable from a taxing authority; and (c) non-current tax expense, which represents the increases and decreases in amounts related to uncertain tax positions from prior periods and not settled with cash or other tax attributes.

The Group recognizes deferred tax assets and liabilities for temporary differences between the financial statement and income tax bases of assets and liabilities, which are measured using enacted tax rates and laws that will be in effect when the differences are expected to reverse. A valuation allowance is provided when it is more likely than not that some portion or all of a deferred tax asset will not be realized.

The Group evaluates its uncertain tax positions using the provisions of ASC 740, Income Taxes, which requires that realization of an uncertain income tax position be recognized in the financial statements. The benefit to be recorded in the financial statements is the amount most likely to be realized assuming a review by tax authorities having all relevant information and applying current conventions. It is the Group's policy to recognize interest and penalties related to unrecognized tax benefits, if any, as a component of income tax expense. No unrecognized tax benefits and related interest and penalties were recorded in any of the periods presented.

Basic earnings (loss) per ordinary share is computed by dividing net income (loss) attributable to ordinary shareholders by weighted average number of ordinary shares outstanding during the period.

The Group's convertible preferred shares are participating securities as the preferred shares participate in undistributed earnings on an as-if-converted basis. Accordingly, the Group uses the two-class method whereby undistributed net income is allocated on a pro rata basis to each participating share to the extent that each class may share income for the period. Undistributed net loss is not allocated to preferred shares because they are not contractually obligated to participate in the loss allocated to the ordinary shares.

Diluted earnings (loss) per ordinary share reflects the potential dilution that could occur if securities were exercised or converted into ordinary shares. The Group had convertible preferred shares, warrants, stock options and non-vested restricted shares, which could potentially dilute basic earnings (loss) per share in the future. To calculate the number of shares for diluted earnings (loss) per share, the effect of the convertible redeemable preferred shares and warrants is computed using the as-if-converted method; the effect of the stock options and non-vested restricted shares is computed using the treasury stock method. The computation of diluted earnings (loss) per share does not assume exercise or conversion of securities that would have an anti‑dilutive effect.

In accordance with ASC 280, Segment Reporting, the Group's chief operating decision maker, the Chief Executive Officer, reviews the consolidated results when making decisions about allocating resources and assessing performance of the Group as a whole and hence, the Group has only one reportable segment. The Group does not distinguish between markets or segments for the purpose of internal reporting. As the Group's long-lived assets are substantially located in and derived from the PRC, no geographical segments are presented.

The following suppliers accounted for 10% or more of research and development expenses for the years ended December 31, 2016, 2017 and 2018:

	Year ended December 31,
	2016		2017		2018
	$		$		$
A		14,625,500	*		*
B	*			7,651,617	*
C	*			7,104,015	*
D	*		*			25,515,178
E	*		*			14,664,364

*	Represents less than 10% of research and development expenses for the years ended December 31, 2016, 2017 and 2018.

Concentration of credit risk

Financial instruments that are potentially subject to significant concentration of credit risk consist of cash and cash equivalents, short-term investments, and prepayments to suppliers. The carrying amounts of cash and cash equivalents and short-term investments represent the maximum amount of loss due to credit risk. As of December 31, 2017 and 2018, all of the Group’s cash and cash equivalents and short-term investments were held by major financial institutions located in the PRC and international financial institutions outside of the PRC which management believes are of high credit quality and continually monitors the credit worthiness of these financial institutions. With respect to the prepayments to suppliers, the Group performs on-going credit evaluations of the financial condition of these suppliers.

Foreign currency risk

Renminbi (“RMB”) is not a freely convertible currency. The State Administration of Foreign Exchange, under the authority of the People's Bank of China, controls the conversion of RMB into foreign currencies. The value of RMB is subject to changes in central government policies and to international economic and political developments affecting supply and demand in the China Foreign Exchange Trading System market. The cash and cash equivalents of the Group included aggregated amounts of RMB25,660,869 and RMB26,878,093, which were denominated in RMB, as of December 31, 2017 and 2018, respectively, representing 2% and 6% of the cash and cash equivalents as of December 31, 2017 and 2018, respectively.

On August 30, 2017, the Company effected a six-to-one share consolidation of all the ordinary shares and preferred shares. All number of shares, par value and per share amounts for all periods presented in these consolidated financial statements and accompanying notes have been adjusted retrospectively, where applicable, to reflect this share consolidation.

In February 2016, the FASB issued ASU 2016-02, Leases (Topic 842), which requires lessees to recognize leases on balance sheet and disclose key information about leasing arrangements. The new standard establishes a right-of-use (ROU) model that requires a lessee to recognize a ROU asset and lease liability on the balance sheet for all leases with terms of longer than 12 months. Leases will be classified as finance or operating, with classification affecting the pattern and classification of expense recognition in the income statement. The standard is effective on January 1, 2019, with early adoption permitted. The Group adopted the new standard on January 1, 2019 and used the effective date as the date of initial application. In July 2018, the FASB issued an update that provided an additional transition option that allows companies to continue applying the guidance under the lease standard in effect at that time in the comparative periods presented in the consolidated financial statements. Companies that elect this option would record a cumulative-effect adjustment to the opening balance of retained earnings on the date of adoption. The Group elected this optional transition method. As of December 31, 2018, the Group has $3.3 million of future minimum operating lease commitments that are not currently recognized on its consolidated balance sheets (see Note 19). Therefore, the Group would expect changes to its consolidated balance sheets for the recognition of these and any additional leases entered into in the future upon adoption.

In June 2018, the FASB issued ASU 2018-07, Compensation—Stock Compensation (Topic 718): Improvements to Nonemployee Share-Based Payment Accounting, which intended to reduce cost and complexity and to improve financial reporting for nonemployee share-based payments. The ASU expands the scope of Topic 718, Compensation—Stock Compensation (which currently only includes share-based payments to employees) to include share-based payments issued to nonemployees for goods or services. Consequently, the accounting for share-based payments to nonemployees and employees will be substantially aligned. The ASU supersedes Subtopic 505-50, Equity—Equity-Based Payments to Non-Employees. The amendments in this ASU are effective for public companies for fiscal years beginning after December 15, 2018, including interim periods within that fiscal year. Early adoption is permitted, but no earlier than a company’s adoption date of Topic 606, Revenue from Contracts with Customers. As of December 31, 2018, there was $93,822 of total unrecognized compensation expense related to unvested non-employee options or restricted shares. The Group does not expect the requirements of ASU 2018-07 will have a material impact on the consolidated financial statements.

In August 2018, the FASB issued ASU 2018-13, Fair Value Measurement (Topic 820): The amendments in ASU 2018-13 eliminate the requirements to disclose the amount and reasons for transfers between Level 1 and Level 2 of the fair value hierarchy, valuation processes for Level 3 fair value measurements, and policy for timing of transfers between levels. ASU 2018-13 also provides clarification in the measurement uncertainty disclosure by explaining that the disclosure is to communicate information about the uncertainty in measurement as of the reporting date. In addition, ASU 2018-13 added the following requirements: changes in unrealized gains and losses for the period included in other comprehensive income for recurring Level 3 fair value measurements held at the end of the reporting period; and range and weighted average of significant unobservable inputs used in Level 3 fair value measurements. Finally, ASU 2018-13 updated language to further encourage entities to apply materiality when considering de minimis for disclosure requirements. The guidance will be applied retrospectively for fiscal years beginning after December 15, 2019, and interim periods within those fiscal years, with the exception of amendments to changes in unrealized gains and losses, the range and weighted average of significant unobservable inputs used for Level 3 fair value measurements, and the narrative description of measurement uncertainty which will be applied prospectively. Early adoption is permitted. The Group does not expect the requirements of ASU 2018-13 will have a material impact on the consolidated financial statements.

In November 2018, the FASB issued ASU 2018-18, Collaborative Arrangements (Topic 808): Clarifying the Interaction between Topic 808 and Topic 606. This update clarifies that certain transactions between participants in a collaborative arrangement should be accounted for under ASC 606 when the counterparty is a customer and precludes an entity from presenting consideration from a transaction in a collaborative arrangement as revenue from contracts with customers if the counterparty is not a customer for that transaction. The update is effective in fiscal years beginning after December 15, 2019, and interim periods therein, and early adoption is permitted for entities that have adopted ASC 606. This guidance should be applied retrospectively to the date of initial application of Topic 606. The Group is currently evaluating the impact on its financial statements of adopting this guidance.