in particular , we expect our expenses to increase as we continue our development of , and seek regulatory approvals for , our product candidates , and begin to commercialize any approved products , as well as hire additional personnel , develop commercial infrastructure , pay fees to outside consultants , lawyers and accountants , and incur increased costs associated with being a public company , such as expenses related to services associated with maintaining compliance with nasdaq listing rules and sec reporting requirements , insurance and investor relations . our net losses may fluctuate significantly from quarter-to-quarter and year-to-year , depending upon the timing of our clinical trials and our expenditures on other research and development activities . cash used to fund operating expenses is impacted by the timing of when we pay these expenses , as reflected in the change in our accounts payable and accrued research and development and other current liabilities . recent developments initial public offering on september 29 , 2020 , we completed our ipo . as a result of the ipo , we issued and sold an aggregate of 6,468,750 shares of our common stock ( inclusive of 843,750 shares issued and sold pursuant to the exercise of the underwriters ' option to purchase additional shares on october 22 , 2020 ) at a price of $ 16.00 per share for net proceeds of $ 92.0 million , after deducting underwriting discounts , commissions and offering expenses . prior to the completion of the ipo , all 117,809,883 shares of our redeemable convertible preferred stock then outstanding were converted into 13,085,913 shares of common stock . business effects of covid-19 the current covid-19 pandemic has presented a substantial public health and economic challenge around the world and is affecting our employees , patients , clinicians , communities and business operations , as well as the u.s. economy and financial markets . to date , our financial condition and operations have not been significantly impacted by the covid-19 outbreak ; however , the full extent to which the covid-19 pandemic will directly or indirectly impact our business , results of operations , liquidity and financial 77 condition will depend on future developments , which are highly uncertain and can not be accurately predicted , including new information that may emerge concerning covid-19 , the actions taken to contain it or treat its impact and the economic impact on local , regional , national and international markets . to date , our contract research organizations , or cros , contract manufacturing organizations , or cmos , and other vendors have been able to continue to provide services and supply reagents , materials , and products and currently do not anticipate any disruption in services or interruptions in supply . our cmos continue to operate their manufacturing facilities at or near normal levels . while we currently do not anticipate any interruptions in our manufacturing process , it is possible that the covid-19 pandemic and response efforts may have an impact in the future on our third-party suppliers ' and contract manufacturing partners ' ability to manufacture reagents , materials or products that we need to use in our research and upcoming clinical trials . however , we are continuing to assess the potential impact of the covid-19 pandemic on our business and operations , including our expenses , our clinical trials , and our ability to hire and retain employees . while we are currently continuing to monitor patients in our altissimo clinical trial at sites across the united states , we expect that covid-19 precautions may directly or indirectly impact the timeline for some of our clinical trial activities due to the inability of patients to come to their monitoring visits , the closing of eye clinics , and or diversion of resources that are necessary to conduct our observational study to care for covid-19 patients . the covid-19 pandemic has caused us to modify our business practices including , but not limited to , curtailing or modifying employee travel , moving to partial remote work , and cancelling physical participation in meetings , events and conferences . we may take further actions as may be required by government authorities or that we determine are in the best interests of our employees , patients , clinicians , and business partners . the majority of our office-based employees have been working from home since march 2020 , while ensuring essential staffing levels to support our operations remain in place , including maintaining key personnel in our laboratories . for additional information on the various risks posed by the covid-19 pandemic , please read item 1a . risk factors . components of operating results research and development expenses our research and development expenses include : personnel costs , which include salaries , benefits and stock-based compensation ; expenses incurred under agreements with consultants and third-party contract organizations that conduct research and development activities on our behalf ; costs related to sponsored research service agreements ; costs related to production of preclinical and clinical materials , including fees paid to contract manufacturers ; laboratory and vendor expenses related to the execution of preclinical studies and planned clinical trials ; milestones and royalty expense from our johns hopkins university exclusive license agreement ; laboratory supplies and materials used for internal research and development activities ; and facilities and equipment costs . most of our research and development expenses have been related to the preclinical and clinical development of gb-102 . we have not reported program costs since inception because we have not historically tracked or recorded our research and development expenses on a program-by-program basis . we use our personnel and infrastructure resources across the breadth of our research and development activities , which are directed toward identifying and developing product candidates . we expense all research and development costs in the periods in which they are incurred . story_separator_special_tag preferred stock tranche obligation convertible preferred stock that includes features we have determined are not clearly and closely related to the equity host are bifurcated and accounted for separately as freestanding derivative assets or liabilities on the balance sheet at their estimated fair value . we recognized a derivative liability as a result of certain investors ' having rights to purchase from us , on the same terms as the series c preferred stock purchase agreement executed in july 2019 , additional shares of our series c preferred stock in subsequent tranches based on the achievement of certain development milestones , or the preferred stock tranche obligation . at initial recognition , we recorded the liability for the preferred stock tranche obligation on the balance sheet at its estimated fair value . this liability was subject to remeasurement at each balance sheet date until the expiration of the preferred stock tranche obligation in september 2020 , with changes in fair value recognized in our statements of operations . the liability for the preferred stock tranche obligation was measured at fair value using an option pricing valuation methodology that included inputs not observable in the market and thus represents a level 3 measurement . the option pricing valuation methodology utilized requires inputs based on certain subjective assumptions , including ( a ) expected stock price volatility , ( b ) calculation of an expected term , ( c ) a risk-free interest rate and ( d ) expected dividends . significant judgment was used in determining these assumptions at initial recognition and at each subsequent reporting period . stock-based compensation we recognize compensation costs related to stock-based awards to employees and non-employees based on the estimated fair value of the awards on the date of grant . we estimate the grant date fair value , and the resulting stock-based compensation , using the black-scholes option-pricing model , or black-scholes . the grant date fair value of the stock-based awards is generally recognized on a straight-line basis over the requisite service period , which is generally the vesting period of the respective awards . black-scholes requires the use of subjective assumptions to determine the fair value of stock-based awards including : fair value of common stock— see subsection entitled “ common stock valuations ” below . expected term—the expected term represents the period that stock-based awards are expected to be outstanding . the expected term for option grants is determined using the simplified method . the simplified method deems the expected term to be the midpoint between the vesting date and the contractual life of the stock-based awards . expected volatility— since we were a privately held company until september 2020 , and do not yet have sufficient trading history for our common stock , the expected volatility is estimated based on the average volatility for comparable publicly traded biotechnology companies over a period equal to the expected term of the stock option grants . the comparable companies were chosen based on their similar size , stage in the life cycle or area of specialty . we will continue to apply this method until a sufficient amount of historical information over a period equal to the expected term of the stock-based awards becomes available . 84 risk-free interest rate—the risk-free interest rate is based on the u.s. treasury zero coupon issues in effect at the time of grant for periods corresponding with the expected term of the option . expected dividend—we have never paid dividends on our common stock and have no plans to pay dividends on our common stock . therefore , we used an expected dividend yield of zero . we will continue to use judgment in evaluating the assumptions utilized for our stock-based compensation expense calculations on a prospective basis . in addition to the assumptions used in black-scholes , the amount of stock-based compensation expense we recognize in our financial statements includes stock option forfeitures as they occur . such assumptions involve inherent uncertainties and the application of significant judgment . as a result , if factors or expected outcomes change and we use significantly different assumptions or estimates , our stock-based compensation could be materially different . common stock valuations historically , for all periods prior to our ipo , the fair value of the shares of common stock underlying our stock-based awards was estimated on each grant date by our board of directors . in the absence of a public trading market for our common stock , our board of directors exercised their judgment and considered a number of objective and subjective factors to determine the best estimate of the fair value of our common stock , including contemporaneous valuations , our stage of development , important developments in our operations , the prices at which we sold shares of our preferred stock , the rights , preferences and privileges of our preferred stock relative to those of our common stock , actual operating results and financial performance , the conditions in the biotechnology industry and the economy in general , the stock price performance and volatility of comparable public companies , and the lack of liquidity of our common stock , among other factors . in determining the fair value of our common stock , the methodologies used to estimate our enterprise value were performed using methodologies , approaches and assumptions consistent with the guidance outlined in the american institute of certified public accountants technical practice aid , valuation of privately held company equity securities issued as compensation . the grant date fair value of our common stock was determined using valuation methodologies incorporating a number of assumptions including probability weighting of events , volatility , time to liquidation , a risk-free interest rate and an assumption for a discount for lack of marketability ( level 3 inputs ) . the methodology to determine the fair value of our common stock included estimating the fair value of the enterprise using a hybrid-method market approach ,

cash flows the following table summarizes our cash flows for the periods indicated : replace_table_token_4_th 82 operating activities cash used in operating activities of $ 32.1 million during the year ended december 31 , 2020 was primarily attributable to our net loss of $ 27.5 million and an increase of $ 4.6 million in our working capital . cash used in operating activities of $ 31.2 million during the year ended december 31 , 2019 was attributable to our net loss of $ 37.0 million , partially offset by a $ 4.9 million decrease in our working capital and non-cash charges of $ 0.9 million principally with respect to stock-based compensation and depreciation expense . investing activities cash used in investing activities of $ 42.6 million during the year ended december 31 , 2020 consisted of $ 61.6 million of purchases of short-term investments and $ 1.0 million of purchases of property and equipment , partially offset by $ 20.0 million provided upon maturity of short-term investments . cash used in investing activities of $ 20.6 million during the year ended december 31 , 2019 consisted of $ 22.5 million of purchases of short-term investments and $ 0.6 million of purchases of property and equipment , partially offset by $ 2.5 million provided upon maturity of short-term investments . financing activities cash provided by financing activities of $ 92.2 million for the year ended december 31 , 2020 consisted of $ 96.3 million of proceeds , net of the underwriters ' discounts and commissions , from the issuance of common stock in connection with our ipo and $ 0.1 million received from the exercise of stock options , partially offset by $ 4.2 million related to the payments of offering costs .


 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 flows the following table summarizes our cash flows for the periods indicated : replace_table_token_4_th 82 operating activities cash used in operating activities of $ 32.1 million during the year ended december 31 , 2020 was primarily attributable to our net loss of $ 27.5 million and an increase of $ 4.6 million in our working capital . cash used in operating activities of $ 31.2 million during the year ended december 31 , 2019 was attributable to our net loss of $ 37.0 million , partially offset by a $ 4.9 million decrease in our working capital and non-cash charges of $ 0.9 million principally with respect to stock-based compensation and depreciation expense . investing activities cash used in investing activities of $ 42.6 million during the year ended december 31 , 2020 consisted of $ 61.6 million of purchases of short-term investments and $ 1.0 million of purchases of property and equipment , partially offset by $ 20.0 million provided upon maturity of short-term investments . cash used in investing activities of $ 20.6 million during the year ended december 31 , 2019 consisted of $ 22.5 million of purchases of short-term investments and $ 0.6 million of purchases of property and equipment , partially offset by $ 2.5 million provided upon maturity of short-term investments . financing activities cash provided by financing activities of $ 92.2 million for the year ended december 31 , 2020 consisted of $ 96.3 million of proceeds , net of the underwriters ' discounts and commissions , from the issuance of common stock in connection with our ipo and $ 0.1 million received from the exercise of stock options , partially offset by $ 4.2 million related to the payments of offering costs .
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 Suspicious Activity Report : in particular , we expect our expenses to increase as we continue our development of , and seek regulatory approvals for , our product candidates , and begin to commercialize any approved products , as well as hire additional personnel , develop commercial infrastructure , pay fees to outside consultants , lawyers and accountants , and incur increased costs associated with being a public company , such as expenses related to services associated with maintaining compliance with nasdaq listing rules and sec reporting requirements , insurance and investor relations . our net losses may fluctuate significantly from quarter-to-quarter and year-to-year , depending upon the timing of our clinical trials and our expenditures on other research and development activities . cash used to fund operating expenses is impacted by the timing of when we pay these expenses , as reflected in the change in our accounts payable and accrued research and development and other current liabilities . recent developments initial public offering on september 29 , 2020 , we completed our ipo . as a result of the ipo , we issued and sold an aggregate of 6,468,750 shares of our common stock ( inclusive of 843,750 shares issued and sold pursuant to the exercise of the underwriters ' option to purchase additional shares on october 22 , 2020 ) at a price of $ 16.00 per share for net proceeds of $ 92.0 million , after deducting underwriting discounts , commissions and offering expenses . prior to the completion of the ipo , all 117,809,883 shares of our redeemable convertible preferred stock then outstanding were converted into 13,085,913 shares of common stock . business effects of covid-19 the current covid-19 pandemic has presented a substantial public health and economic challenge around the world and is affecting our employees , patients , clinicians , communities and business operations , as well as the u.s. economy and financial markets . to date , our financial condition and operations have not been significantly impacted by the covid-19 outbreak ; however , the full extent to which the covid-19 pandemic will directly or indirectly impact our business , results of operations , liquidity and financial 77 condition will depend on future developments , which are highly uncertain and can not be accurately predicted , including new information that may emerge concerning covid-19 , the actions taken to contain it or treat its impact and the economic impact on local , regional , national and international markets . to date , our contract research organizations , or cros , contract manufacturing organizations , or cmos , and other vendors have been able to continue to provide services and supply reagents , materials , and products and currently do not anticipate any disruption in services or interruptions in supply . our cmos continue to operate their manufacturing facilities at or near normal levels . while we currently do not anticipate any interruptions in our manufacturing process , it is possible that the covid-19 pandemic and response efforts may have an impact in the future on our third-party suppliers ' and contract manufacturing partners ' ability to manufacture reagents , materials or products that we need to use in our research and upcoming clinical trials . however , we are continuing to assess the potential impact of the covid-19 pandemic on our business and operations , including our expenses , our clinical trials , and our ability to hire and retain employees . while we are currently continuing to monitor patients in our altissimo clinical trial at sites across the united states , we expect that covid-19 precautions may directly or indirectly impact the timeline for some of our clinical trial activities due to the inability of patients to come to their monitoring visits , the closing of eye clinics , and or diversion of resources that are necessary to conduct our observational study to care for covid-19 patients . the covid-19 pandemic has caused us to modify our business practices including , but not limited to , curtailing or modifying employee travel , moving to partial remote work , and cancelling physical participation in meetings , events and conferences . we may take further actions as may be required by government authorities or that we determine are in the best interests of our employees , patients , clinicians , and business partners . the majority of our office-based employees have been working from home since march 2020 , while ensuring essential staffing levels to support our operations remain in place , including maintaining key personnel in our laboratories . for additional information on the various risks posed by the covid-19 pandemic , please read item 1a . risk factors . components of operating results research and development expenses our research and development expenses include : personnel costs , which include salaries , benefits and stock-based compensation ; expenses incurred under agreements with consultants and third-party contract organizations that conduct research and development activities on our behalf ; costs related to sponsored research service agreements ; costs related to production of preclinical and clinical materials , including fees paid to contract manufacturers ; laboratory and vendor expenses related to the execution of preclinical studies and planned clinical trials ; milestones and royalty expense from our johns hopkins university exclusive license agreement ; laboratory supplies and materials used for internal research and development activities ; and facilities and equipment costs . most of our research and development expenses have been related to the preclinical and clinical development of gb-102 . we have not reported program costs since inception because we have not historically tracked or recorded our research and development expenses on a program-by-program basis . we use our personnel and infrastructure resources across the breadth of our research and development activities , which are directed toward identifying and developing product candidates . we expense all research and development costs in the periods in which they are incurred . story_separator_special_tag preferred stock tranche obligation convertible preferred stock that includes features we have determined are not clearly and closely related to the equity host are bifurcated and accounted for separately as freestanding derivative assets or liabilities on the balance sheet at their estimated fair value . we recognized a derivative liability as a result of certain investors ' having rights to purchase from us , on the same terms as the series c preferred stock purchase agreement executed in july 2019 , additional shares of our series c preferred stock in subsequent tranches based on the achievement of certain development milestones , or the preferred stock tranche obligation . at initial recognition , we recorded the liability for the preferred stock tranche obligation on the balance sheet at its estimated fair value . this liability was subject to remeasurement at each balance sheet date until the expiration of the preferred stock tranche obligation in september 2020 , with changes in fair value recognized in our statements of operations . the liability for the preferred stock tranche obligation was measured at fair value using an option pricing valuation methodology that included inputs not observable in the market and thus represents a level 3 measurement . the option pricing valuation methodology utilized requires inputs based on certain subjective assumptions , including ( a ) expected stock price volatility , ( b ) calculation of an expected term , ( c ) a risk-free interest rate and ( d ) expected dividends . significant judgment was used in determining these assumptions at initial recognition and at each subsequent reporting period . stock-based compensation we recognize compensation costs related to stock-based awards to employees and non-employees based on the estimated fair value of the awards on the date of grant . we estimate the grant date fair value , and the resulting stock-based compensation , using the black-scholes option-pricing model , or black-scholes . the grant date fair value of the stock-based awards is generally recognized on a straight-line basis over the requisite service period , which is generally the vesting period of the respective awards . black-scholes requires the use of subjective assumptions to determine the fair value of stock-based awards including : fair value of common stock— see subsection entitled “ common stock valuations ” below . expected term—the expected term represents the period that stock-based awards are expected to be outstanding . the expected term for option grants is determined using the simplified method . the simplified method deems the expected term to be the midpoint between the vesting date and the contractual life of the stock-based awards . expected volatility— since we were a privately held company until september 2020 , and do not yet have sufficient trading history for our common stock , the expected volatility is estimated based on the average volatility for comparable publicly traded biotechnology companies over a period equal to the expected term of the stock option grants . the comparable companies were chosen based on their similar size , stage in the life cycle or area of specialty . we will continue to apply this method until a sufficient amount of historical information over a period equal to the expected term of the stock-based awards becomes available . 84 risk-free interest rate—the risk-free interest rate is based on the u.s. treasury zero coupon issues in effect at the time of grant for periods corresponding with the expected term of the option . expected dividend—we have never paid dividends on our common stock and have no plans to pay dividends on our common stock . therefore , we used an expected dividend yield of zero . we will continue to use judgment in evaluating the assumptions utilized for our stock-based compensation expense calculations on a prospective basis . in addition to the assumptions used in black-scholes , the amount of stock-based compensation expense we recognize in our financial statements includes stock option forfeitures as they occur . such assumptions involve inherent uncertainties and the application of significant judgment . as a result , if factors or expected outcomes change and we use significantly different assumptions or estimates , our stock-based compensation could be materially different . common stock valuations historically , for all periods prior to our ipo , the fair value of the shares of common stock underlying our stock-based awards was estimated on each grant date by our board of directors . in the absence of a public trading market for our common stock , our board of directors exercised their judgment and considered a number of objective and subjective factors to determine the best estimate of the fair value of our common stock , including contemporaneous valuations , our stage of development , important developments in our operations , the prices at which we sold shares of our preferred stock , the rights , preferences and privileges of our preferred stock relative to those of our common stock , actual operating results and financial performance , the conditions in the biotechnology industry and the economy in general , the stock price performance and volatility of comparable public companies , and the lack of liquidity of our common stock , among other factors . in determining the fair value of our common stock , the methodologies used to estimate our enterprise value were performed using methodologies , approaches and assumptions consistent with the guidance outlined in the american institute of certified public accountants technical practice aid , valuation of privately held company equity securities issued as compensation . the grant date fair value of our common stock was determined using valuation methodologies incorporating a number of assumptions including probability weighting of events , volatility , time to liquidation , a risk-free interest rate and an assumption for a discount for lack of marketability ( level 3 inputs ) . the methodology to determine the fair value of our common stock included estimating the fair value of the enterprise using a hybrid-method market approach ,

