this may have a material adverse effect on our business , financial condition , results of operation , and cash flows . revenue effects related to covid-19 pandemic assay revenue beginning in march 2020 and continuing through the end of 2020 , the ongoing covid-19 pandemic has reduced patient access to clinician offices for in-person testing , which has resulted in a reduced volume of billable samples received relative to our pre-pandemic expectations . april 2020 billable sample volume was down by approximately 80 % , commensurate with the closure of dermatology offices , compared to the average monthly billable sample volume for the two months preceding the beginning of the covid-19 stay-at-home orders . despite the downturn in billable samples in april 2020 , we saw a stabilization of billable sample volume throughout the rest of the second quarter and through the fourth quarter as various states and dermatology offices opened throughout the country . billable sample volume first exceeded pre‑pandemic levels in july 2020 even without all dermatology practices returning to full operations . billable sample volume for the three months ended december 31 , 2020 was 24 % higher than billable sample volume for the three months ended september 30 , 2020 , and billable sample volume for the twelve months ended december 31 , 2020 was 75 % higher than billable sample volume for the twelve months ended december 31 , 2019. billable sample volume for the three months ended december 31 , 2020 was 69 % higher than billable sample volume for the three months ended december 31 , 2019. billable sample volumes could continue to be impacted by the ongoing covid-19 pandemic and further impacted by a resurgence of the virus in the future . 58 we have made available beginning in late april 2020 a telemedicine option for the pla , but the telemedicine market is r elatively new and unproven , especially within dermatology , and it is uncertain whether it will achieve and sustain high levels of demand , consumer acceptance and market adoption . while the covid-19 pandemic is ongoing and clinician offices could close agai n due to the rolling back of reopening plans in various states , or patients could worry about going into the dermatology clinic , we expect that our revenues will depend to an extent on the willingness of clinicians and their patients to use our telemedicin e option for the pla , as well as on our ability to demonstrate the value of our telemedicine option to health plans and other purchasers of healthcare for beneficiaries . we also expect that the duration and extent of the effects of the ongoing covid-19 pan demic in reducing patient access to clinician offices for in-person testing , and access by our sales force for in-office sales calls will adversely affect our revenues . contract revenue contract revenues with major pharmaceutical companies relate to ongoing clinical trial contracts and new contracts . contract revenue can be highly variable as it is dependent on the pharmaceutical customers ' clinical trial progress which can be difficult to forecast due to variability of patient enrollment , drug safety and efficacy and other factors . many of our contracts with third parties are structured to contain milestone billing payments , which typically are advance payments on work yet to be performed . these advanced payments are structured to help fund operations and are included in deferred revenue as the work has not yet been performed . these advance payments will remain in deferred revenue until we process the laboratory portion of the contracts allowing us to recognize the revenue . the ongoing covid-19 pandemic has negatively affected and will continue to negatively affect our pharmaceutical customers ' clinical trials . the extent of such effect on our future revenue is uncertain and will depend on the duration and extent of the effects of the ongoing covid-19 pandemic on our pharmaceutical customers ' clinical trials . financial overview revenue we generate revenue through laboratory services that are billed to medicare , private medical insurance companies and to pharmaceutical companies who order our laboratory services , which can include sample collection kits , assay development , genomic analysis , data analysis and reporting . our revenue is generated from two revenue streams : contract revenue and assay revenue . assay revenue can be highly variable as it is based on payments received by private insurance payors that are not under contract and can vary based on patient insurance coverage , deductibles and co-pays . contract revenue is ordered by customers on projects that may span over several years , which makes this type of revenue highly variable . segments of these contracts may be increased , delayed or eliminated based on the success of each customers ' clinical trials or other factors . operating expenses sales and marketing expenses sales and marketing expenses are primarily related to our specialty field sales force , market research , reimbursement efforts , trade show attendance , public relations , and general marketing . we expect these expenses to increase significantly as we expand our direct consumer marketing efforts and continue to add to our specialty sales force , marketing and payor access teams throughout 2021. research and development expenses our research and development , or r & d , expenses consist primarily of salaries and fringe benefits , clinical trials , consulting costs , facilities costs , laboratory costs , equipment expense , and depreciation . we also conduct clinical trials to validate the performance characteristics of our tests and to show medical cost benefit in support of our reimbursement efforts . we expect these expenses to increase significantly as we continue to develop new products and expand the use of our existing products . story_separator_special_tag because of the numerous risks and uncertainties associated with our commercialization and development efforts , we are unable to predict when we will become profitable , and we may never become profitable . our inability to achieve and then maintain profitability would negatively affect our business , financial condition , results of operations and cash flows . as of december 31 , 2020 , our cash , cash equivalents and marketable securities totaled $ 63.8 million . on january 11 , 2021 , we closed a public offering that resulted in aggregate gross proceeds of $ 143.7 million from the offering , before deducting underwriting discounts and commissions and other offering expenses . based on our current business operations and the additional 2021 financing , we believe our current cash and cash equivalents will be sufficient to meet our anticipated cash requirements for at least the next twelve months . while we believe we have enough capital to fund anticipated operating costs for at least the next 12 months , we expect to incur significant additional operating losses over at least the next several years . we anticipate that we will raise additional capital through equity offerings , debt financings , collaborations or licensing arrangements in order to support our planned operations and to continue developing and commercializing genomic tests . we may also consider raising additional capital in the future to expand our business , to pursue strategic investments or to take advantage of financing opportunities . our present and future funding requirements will depend on many factors , including : our revenue growth rate and ability to generate cash flows from operating activities ; the willingness of clinicians and their patients to use our telemedicine option for the pla and the duration and extent of the effects of the ongoing covid-19 pandemic in reducing patient access to clinician offices for in-person testing ; the duration and extent of the effects of the ongoing covid-19 pandemic on our pharmaceutical customers ' clinical trials ; our sales and marketing and r & d activities ; effects of competing technological and market developments ; costs of and potential delays in product development ; changes in regulatory oversight applicable to our tests ; and timing of and costs related to future international expansion . there can be no assurances as to the availability of additional financing or the terms upon which additional financing may be available to us . if we are unable to obtain sufficient funding at acceptable terms , we may be forced to significantly curtail our operations , and the lack of sufficient funding may have a material adverse impact on our ability to continue as a going concern . story_separator_special_tag assay development for research partners , rna extraction , isolation , expression , amplification and detection , including data analysis and reporting . see note 1 ( k ) of our consolidated financial statements for a full discussion of our revenue recognition policy around assay revenue and contract revenue . stock-based compensation compensation costs associated with stock option awards and other forms of equity compensation are measured at the grant-date fair value of the awards and recognized over the requisite service period of the awards on a ratable basis . we grant stock options to purchase common stock to employees with exercise prices equal to the fair market value of the underlying stock , as determined by the board of directors , management , outside valuation experts and subsequent to the completion of the business combination , the closing stock price on the date of grant . the board of directors and outside valuation experts determine the fair value of the underlying stock by considering a number of factors , including historical and projected financial results , the risks we faced at the time , the preferences of our debt holders and preferred stockholders , and the lack of liquidity of our common stock that occurred prior to the business combination . the fair value of each stock option award is estimated using the black-scholes-merton valuation model . such value is recognized as expense over the requisite service period using the straight-line method . the expected term of options is based on the simplified method which defines the expected term as the average of the contractual term of the options and the weighted average vesting period for all option tranches . the expected volatility of stock options is based upon the historical volatility of a number of related publicly traded companies in similar stages of development as well as the volatility of the company 's common stock . the risk-free interest rate is based on the average yield of u.s. treasury securities with remaining terms similar to the expected term of the share-based awards . the assumed dividend yield was based on our expectation of not paying dividends in the foreseeable future . we account for stock options to non-employees using the fair value approach . the fair value of these options is measured using the black-scholes-merton optio n pricing model , reflecting the same assumptions applied to employee options , other than expected life , which is assumed to be the remaining contractual life of the award . options that are granted to employees generally have a requisite service period of three to four years . 65 restricted stock units ( “ rsus ” ) are considered restricted stock . the fair value of restricted stock is equal to the fair market value of the underlying stock , as determined by the board of directors , management , input from outside valua tion experts and subsequent to the completion of the business combination , the closing stock price on the date of grant . we recognize stock-based compensation expense based on the fair value on a ratable basis over the requisite service periods of the awar ds . rsus that are granted to employees have a requisite service period typically between two and four years . recent

cash flow analysis fiscal year ended december 31 , 2020 net cash used in operating activities for the twelve months ended december 31 , 2020 totaled $ 28.7 million , primarily driven by the $ 35.2 million net loss offset by non-cash related items , including $ 5.0 million in stock-based compensation and $ 0.5 million in depreciation . in addition , we had a cash inflow of $ 0.8 million through the increase of accounts payable and accrued compensation as well as a $ 1.6 million of cash inflow through the increase of accrued liabilities and deferred revenues . this was offset by the cash outflow through the increase of prepaid expenses and other assets of $ 0.5 million as well as an increase in accounts receivable of $ 0.8 million . 63 net cash used in investing activities totaled $ 41.3 million for the twelve months ended december 31 , 2020 , primarily related to the purchas e of $ 41 . 7 million in short-term marketable securities and $ 1 . 8 million in purchases of property and equipment . this was offset by cash inflows from the sale and maturity of marketable securities of $ 2.2 million . as we scale our sales force , the expected t iming of a corresponding increase in assay volume is uncertain due , in part , to challenges presented by the ongoing covid-19 pandemic , such as related limits on patient access to clinician offices for in-person testing . additional laboratory equipment inve stment will be needed to install complex automation systems and other genomic testing equipment needed to expand testing capacit y . net cash provided by financing activities totaled $ 78.9 million for the twelve months ended december 31 , 2020 , which was predominantly driven by the $ 59.9 million and $ 19.1 million in net proceeds raised from the 2020 pipe financing and at-the-market offering , respectively , and $ 1.3 million from the exercise of stock options and warrants . this was offset by the payment made by the company of the deferred underwriting fees of $ 1.4 million .


 Write a concise suspicious activity report of the following text delimited by triple backquotes. Return your response as a formal report which covers the key points highlighting the location,dates,entity names and account holder information in chronological order of the text.
     ```cash flow analysis fiscal year ended december 31 , 2020 net cash used in operating activities for the twelve months ended december 31 , 2020 totaled $ 28.7 million , primarily driven by the $ 35.2 million net loss offset by non-cash related items , including $ 5.0 million in stock-based compensation and $ 0.5 million in depreciation . in addition , we had a cash inflow of $ 0.8 million through the increase of accounts payable and accrued compensation as well as a $ 1.6 million of cash inflow through the increase of accrued liabilities and deferred revenues . this was offset by the cash outflow through the increase of prepaid expenses and other assets of $ 0.5 million as well as an increase in accounts receivable of $ 0.8 million . 63 net cash used in investing activities totaled $ 41.3 million for the twelve months ended december 31 , 2020 , primarily related to the purchas e of $ 41 . 7 million in short-term marketable securities and $ 1 . 8 million in purchases of property and equipment . this was offset by cash inflows from the sale and maturity of marketable securities of $ 2.2 million . as we scale our sales force , the expected t iming of a corresponding increase in assay volume is uncertain due , in part , to challenges presented by the ongoing covid-19 pandemic , such as related limits on patient access to clinician offices for in-person testing . additional laboratory equipment inve stment will be needed to install complex automation systems and other genomic testing equipment needed to expand testing capacit y . net cash provided by financing activities totaled $ 78.9 million for the twelve months ended december 31 , 2020 , which was predominantly driven by the $ 59.9 million and $ 19.1 million in net proceeds raised from the 2020 pipe financing and at-the-market offering , respectively , and $ 1.3 million from the exercise of stock options and warrants . this was offset by the payment made by the company of the deferred underwriting fees of $ 1.4 million .
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 Suspicious Activity Report : this may have a material adverse effect on our business , financial condition , results of operation , and cash flows . revenue effects related to covid-19 pandemic assay revenue beginning in march 2020 and continuing through the end of 2020 , the ongoing covid-19 pandemic has reduced patient access to clinician offices for in-person testing , which has resulted in a reduced volume of billable samples received relative to our pre-pandemic expectations . april 2020 billable sample volume was down by approximately 80 % , commensurate with the closure of dermatology offices , compared to the average monthly billable sample volume for the two months preceding the beginning of the covid-19 stay-at-home orders . despite the downturn in billable samples in april 2020 , we saw a stabilization of billable sample volume throughout the rest of the second quarter and through the fourth quarter as various states and dermatology offices opened throughout the country . billable sample volume first exceeded pre‑pandemic levels in july 2020 even without all dermatology practices returning to full operations . billable sample volume for the three months ended december 31 , 2020 was 24 % higher than billable sample volume for the three months ended september 30 , 2020 , and billable sample volume for the twelve months ended december 31 , 2020 was 75 % higher than billable sample volume for the twelve months ended december 31 , 2019. billable sample volume for the three months ended december 31 , 2020 was 69 % higher than billable sample volume for the three months ended december 31 , 2019. billable sample volumes could continue to be impacted by the ongoing covid-19 pandemic and further impacted by a resurgence of the virus in the future . 58 we have made available beginning in late april 2020 a telemedicine option for the pla , but the telemedicine market is r elatively new and unproven , especially within dermatology , and it is uncertain whether it will achieve and sustain high levels of demand , consumer acceptance and market adoption . while the covid-19 pandemic is ongoing and clinician offices could close agai n due to the rolling back of reopening plans in various states , or patients could worry about going into the dermatology clinic , we expect that our revenues will depend to an extent on the willingness of clinicians and their patients to use our telemedicin e option for the pla , as well as on our ability to demonstrate the value of our telemedicine option to health plans and other purchasers of healthcare for beneficiaries . we also expect that the duration and extent of the effects of the ongoing covid-19 pan demic in reducing patient access to clinician offices for in-person testing , and access by our sales force for in-office sales calls will adversely affect our revenues . contract revenue contract revenues with major pharmaceutical companies relate to ongoing clinical trial contracts and new contracts . contract revenue can be highly variable as it is dependent on the pharmaceutical customers ' clinical trial progress which can be difficult to forecast due to variability of patient enrollment , drug safety and efficacy and other factors . many of our contracts with third parties are structured to contain milestone billing payments , which typically are advance payments on work yet to be performed . these advanced payments are structured to help fund operations and are included in deferred revenue as the work has not yet been performed . these advance payments will remain in deferred revenue until we process the laboratory portion of the contracts allowing us to recognize the revenue . the ongoing covid-19 pandemic has negatively affected and will continue to negatively affect our pharmaceutical customers ' clinical trials . the extent of such effect on our future revenue is uncertain and will depend on the duration and extent of the effects of the ongoing covid-19 pandemic on our pharmaceutical customers ' clinical trials . financial overview revenue we generate revenue through laboratory services that are billed to medicare , private medical insurance companies and to pharmaceutical companies who order our laboratory services , which can include sample collection kits , assay development , genomic analysis , data analysis and reporting . our revenue is generated from two revenue streams : contract revenue and assay revenue . assay revenue can be highly variable as it is based on payments received by private insurance payors that are not under contract and can vary based on patient insurance coverage , deductibles and co-pays . contract revenue is ordered by customers on projects that may span over several years , which makes this type of revenue highly variable . segments of these contracts may be increased , delayed or eliminated based on the success of each customers ' clinical trials or other factors . operating expenses sales and marketing expenses sales and marketing expenses are primarily related to our specialty field sales force , market research , reimbursement efforts , trade show attendance , public relations , and general marketing . we expect these expenses to increase significantly as we expand our direct consumer marketing efforts and continue to add to our specialty sales force , marketing and payor access teams throughout 2021. research and development expenses our research and development , or r & d , expenses consist primarily of salaries and fringe benefits , clinical trials , consulting costs , facilities costs , laboratory costs , equipment expense , and depreciation . we also conduct clinical trials to validate the performance characteristics of our tests and to show medical cost benefit in support of our reimbursement efforts . we expect these expenses to increase significantly as we continue to develop new products and expand the use of our existing products . story_separator_special_tag because of the numerous risks and uncertainties associated with our commercialization and development efforts , we are unable to predict when we will become profitable , and we may never become profitable . our inability to achieve and then maintain profitability would negatively affect our business , financial condition , results of operations and cash flows . as of december 31 , 2020 , our cash , cash equivalents and marketable securities totaled $ 63.8 million . on january 11 , 2021 , we closed a public offering that resulted in aggregate gross proceeds of $ 143.7 million from the offering , before deducting underwriting discounts and commissions and other offering expenses . based on our current business operations and the additional 2021 financing , we believe our current cash and cash equivalents will be sufficient to meet our anticipated cash requirements for at least the next twelve months . while we believe we have enough capital to fund anticipated operating costs for at least the next 12 months , we expect to incur significant additional operating losses over at least the next several years . we anticipate that we will raise additional capital through equity offerings , debt financings , collaborations or licensing arrangements in order to support our planned operations and to continue developing and commercializing genomic tests . we may also consider raising additional capital in the future to expand our business , to pursue strategic investments or to take advantage of financing opportunities . our present and future funding requirements will depend on many factors , including : our revenue growth rate and ability to generate cash flows from operating activities ; the willingness of clinicians and their patients to use our telemedicine option for the pla and the duration and extent of the effects of the ongoing covid-19 pandemic in reducing patient access to clinician offices for in-person testing ; the duration and extent of the effects of the ongoing covid-19 pandemic on our pharmaceutical customers ' clinical trials ; our sales and marketing and r & d activities ; effects of competing technological and market developments ; costs of and potential delays in product development ; changes in regulatory oversight applicable to our tests ; and timing of and costs related to future international expansion . there can be no assurances as to the availability of additional financing or the terms upon which additional financing may be available to us . if we are unable to obtain sufficient funding at acceptable terms , we may be forced to significantly curtail our operations , and the lack of sufficient funding may have a material adverse impact on our ability to continue as a going concern . story_separator_special_tag assay development for research partners , rna extraction , isolation , expression , amplification and detection , including data analysis and reporting . see note 1 ( k ) of our consolidated financial statements for a full discussion of our revenue recognition policy around assay revenue and contract revenue . stock-based compensation compensation costs associated with stock option awards and other forms of equity compensation are measured at the grant-date fair value of the awards and recognized over the requisite service period of the awards on a ratable basis . we grant stock options to purchase common stock to employees with exercise prices equal to the fair market value of the underlying stock , as determined by the board of directors , management , outside valuation experts and subsequent to the completion of the business combination , the closing stock price on the date of grant . the board of directors and outside valuation experts determine the fair value of the underlying stock by considering a number of factors , including historical and projected financial results , the risks we faced at the time , the preferences of our debt holders and preferred stockholders , and the lack of liquidity of our common stock that occurred prior to the business combination . the fair value of each stock option award is estimated using the black-scholes-merton valuation model . such value is recognized as expense over the requisite service period using the straight-line method . the expected term of options is based on the simplified method which defines the expected term as the average of the contractual term of the options and the weighted average vesting period for all option tranches . the expected volatility of stock options is based upon the historical volatility of a number of related publicly traded companies in similar stages of development as well as the volatility of the company 's common stock . the risk-free interest rate is based on the average yield of u.s. treasury securities with remaining terms similar to the expected term of the share-based awards . the assumed dividend yield was based on our expectation of not paying dividends in the foreseeable future . we account for stock options to non-employees using the fair value approach . the fair value of these options is measured using the black-scholes-merton optio n pricing model , reflecting the same assumptions applied to employee options , other than expected life , which is assumed to be the remaining contractual life of the award . options that are granted to employees generally have a requisite service period of three to four years . 65 restricted stock units ( “ rsus ” ) are considered restricted stock . the fair value of restricted stock is equal to the fair market value of the underlying stock , as determined by the board of directors , management , input from outside valua tion experts and subsequent to the completion of the business combination , the closing stock price on the date of grant . we recognize stock-based compensation expense based on the fair value on a ratable basis over the requisite service periods of the awar ds . rsus that are granted to employees have a requisite service period typically between two and four years . recent

