in march 2020 , the world health organization declared the covid-19 outbreak to be a pandemic . since then , the covid-19 pandemic has rapidly spread across the globe and has already resulted in significant volatility , uncertainty , and economic disruption . thus far , the impact of the pandemic has been modest with some customers , particularly in heavily impacted industries , requesting special billing or payment terms . our gross retention rate for the fourth quarter of fiscal 2021 remained consistently high and our dollar-based net retention rate once again exceeded 120 percent as we continued to expand module adoption within new and existing customers . in march 2020 , we implemented several measures to help protect the health and safety of our employees around the globe including restricting all travel and transitioning 100 % of our workforce to be remote . in addition , in response to the uncertain macroeconomic environment , we converted all of our marketable securities to cash and cash equivalents , and as of january 31 , 2021 , all of our investments were classified as cash . 57 we continue to conduct business as usual with modifications to employee travel , employee work locations , customer interactions , and cancellation of certain marketing events , among other things . we will continue to actively monitor the situation and may take further actions that alter our business operations as may be required by federal , state , or local authorities , or that we determine are in the best interests of our employees , customers , partners , suppliers , and stockholders . the extent to which the covid-19 pandemic may impact our longer-term operational and financial performance remains uncertain . furthermore , due to our subscription-based business model , the effect of the covid-19 pandemic may not be fully reflected in our results of operations until future periods , if at all . the extent of the impact of the covid-19 pandemic will depend on several factors , including the pace of reopening the economy around the world ; the possible resurgence in the spread of the virus ; the development cycle of therapeutics and vaccines ; the impact on our customers and our sales cycles ; the impact on our customer , employee , and industry events ; and the effect on our vendors . please see part i , item 1a , “ risk factors ” in this annual report on form 10-k for a further description of the material risks we currently face , including risks related to the covid-19 pandemic . in march 2020 , we launched two initiatives to help our customers quickly onboard new remote workers without sacrificing protection or having to worry about a procurement cycle . this included a surge relief plan that allows our customers to surge the number of endpoints for a limited time . additionally , we launched a falcon prevent for home use program that allows our customers ' company administrators to install falcon prevent on their employees ' home systems . we believe both of these initiatives have been well received by our customers . on september 30 , 2020 , we acquired preempt security , a privately-held delaware corporation that developed real-time access control and threat prevention technology ( the “ acquisition ” ) . the total consideration transferred was $ 91.2 million which consisted of $ 87.4 million in cash and $ 3.8 million representing the fair value of replacement equity awards attributable to pre-acquisition service . the purchase price was allocated , on a preliminary basis , to identified intangible assets , which include developed technology , customer relationships and trade names , of $ 16.4 million , net tangible assets acquired of $ ( 0.5 ) million and goodwill of $ 75.3 million , representing the excess of the purchase price over the fair value of net tangible and intangible assets acquired . with this acquisition , we plan to offer customers enhanced zero trust security capabilities and strengthen our falcon platform with conditional access technology . the addition of preempt security 's technology to the falcon platform will help customers achieve end-to-end visibility and enforcement on identity data . on january 4 , 2021 , we amended and restated our existing credit agreement ( the “ a & r credit agreement ” and the facility thereunder the “ revolving facility ” ) among crowdstrike , inc. , as borrower , crowdstrike holdings , inc. , as guarantor , and silicon valley bank and the other lenders party thereto , providing us with a revolving line of credit of up to $ 750.0 million , including a letter of credit sub-facility in the aggregate amount of $ 100.0 million , and a swingline sub-facility in the aggregate amount of $ 50.0 million . we also have the option to request an incremental facility of up to an additional $ 250.0 million from one or more of the lenders under the a & r credit agreement . the a & r credit agreement is guaranteed by all of our material domestic subsidiaries . the maturity date under the a & r credit agreement is january 2 , 2026. on january 20 , 2021 , we issued and sold $ 750.0 million aggregate principal amount of 3.000 % senior notes due 2029 ( the “ senior notes ” ) . the senior notes are guaranteed by one of our subsidiaries , crowdstrike , inc. , as of the closing date , and thereafter will be guaranteed by any of our domestic subsidiaries that become borrowers or guarantors under our senior secured revolving credit facility . the senior notes and the guarantee are general unsecured senior obligations and rank equal in right of payment to all of our existing and future senior indebtedness . interest will be payable semi-annually at a rate of 3.000 % per year . story_separator_special_tag 62 interest expense : interest expense consists primarily of interest expense on our secured revolving credit facility , interest expense from amortization of debt issuance costs , and contractual interest expense for our senior notes issued in january 2021. we expect interest expense to be higher in fiscal 2022 as a result of the issuance of our senior notes . other income ( expense ) , net . other income ( expense ) , net , consists primarily of income earned on our cash equivalents and marketable securities ; expense related to the fair value of warrants for our redeemable convertible preferred stock and foreign currency transaction gains and losses . provision for income taxes . provision for income taxes consists of federal and state income taxes in the united states and income taxes and withholding taxes related to customer payments in certain foreign jurisdictions in which we conduct business . we maintain a full valuation allowance on our u.s. federal and state and uk deferred tax assets that we have determined are not realizable on a more likely than not basis . results of operations the following tables set forth our consolidated statements of operations in dollar amounts and as a percentage of total revenue for each period presented : replace_table_token_11_th ( 1 ) includes stock-based compensation expense as follows : replace_table_token_12_th 63 ( 2 ) includes amortization of acquired intangible assets as follows : replace_table_token_13_th ( 3 ) includes acquisition-related expenses as follows : year ended january , 31 2021 2020 2019 ( in thousands ) general and administrative $ 3,758 $ — $ — total acquisition-related expenses $ 3,758 $ — $ — ( 4 ) includes amortization of debt issuance costs and discount as follows : replace_table_token_14_th the following table presents the components of our consolidated statements of operations as a percentage of total revenue for the periods presented : replace_table_token_15_th 64 comparison of fiscal 2021 and fiscal 2020 revenue the following shows total revenue from subscriptions and professional services for fiscal 2021 , as compared to fiscal 2020 : replace_table_token_16_th total revenue increased by $ 393.0 million , or 82 % , in fiscal 2021 , compared to fiscal 2020. subscription revenue accounted for 92 % of our total revenue in fiscal 2021 , and 91 % in fiscal 2020. professional services revenue accounted for 8 % of our total revenue in fiscal 2021 and 9 % in fiscal 2020. subscription revenue increased by $ 368.3 million , or 84 % , in fiscal 2021 , compared to fiscal 2020. this increase was primarily attributable to the addition of new subscription customers , as we increased our customer base by 82 % , fro m 5,431 subscription customers in fiscal 2020 to 9,896 subscription customers in fiscal 2021. s ubscription revenue from new customers , subscription revenue from the renewal of existing customers , and subscription revenue from the sale of additional endpoints and additional modules to existing customers accounted for 33 % , 36 % , and 31 % of total subscription revenue in fiscal 2021 , respectively . subscription revenue from new customers , subscription revenue from the renewal of existing customers , and subscription revenue from the sale of additional endpoints and additional modules to existing customers accounted for 40 % , 33 % , and 27 % of total subscription revenue in fiscal 2020 , respectively . professional services revenue increased by $ 24.7 million , or 55 % , in fiscal 2021 , compared to fiscal 2020 , and was primarily attributable to an increase in the number of professional service hours performed . the following shows cost of revenue related to subscriptions and professional services for fiscal 2021 , as compared to fiscal 2020 : replace_table_token_17_th total cost of revenue increased by $ 87.9 million , or 62 % , in fiscal 2021 , compared to fiscal 2020. subscription cost of revenue increased by $ 72.7 million , or 65 % , in fiscal 2021 , compared to fiscal 2020. the increase in subscription cost of revenue was primarily due to an increase in employee-related expenses of $ 27.6 million driven by a 74 % increase in average headcount , an increase in cloud hosting and related services of $ 23.3 million driven by increased customer activity , an increase in depreciation of data center equipment of $ 7.8 million , an increase in stock-based compensation expense of $ 6.5 million , an increase in allocated overhead costs of $ 4.1 million , an increase in the amortization of internal use software of $ 1.6 million , and an increase in employee health insurance expense of $ 1.4 million , partially offset by a $ 1.2 million decrease in travel related costs due to the fact that , as a result of the covid-19 pandemic , a majority of our workforce was working remotely and incurred limited travel costs during fiscal 2021. professional services cost of revenue increased by $ 15.2 million , or 52 % , in fiscal 2021 , compared to fiscal 2020. the increase in professional services cost of revenue was primarily due to an increase in employee-related expenses of $ 11.4 million driven by an increase in average headcount of 47 % and an increase in stock-based compensation expense of $ 3.5 million , partially offset by a $ 1.1 million decrease in travel related costs due to the fact that , as a result of the covid-19 pandemic , a majority of our workforce was working remotely and incurred limited travel costs during fiscal 2021 . 65 the following shows gross profit and gross margin for subscriptions and professional services for fiscal 2021 , as compared to fiscal 2020. replace_table_token_18_th replace_table_token_19_th subscription gross margin increased by 3 % , in fiscal 2021 , compared to fiscal 2020. this increase was a result of continuing to shift more of our operations from third-party cloud service providers to colocation data centers , renegotiating the terms of

cash flows the following table summarizes our cash flows for the periods presented : replace_table_token_36_th operating activities net cash provided by operating activities during fiscal 2021 was $ 356.6 million , which resulted from a net loss of $ 92.6 million , adjusted for non-cash charges of $ 263.6 million and net cash inflow of $ 185.6 million from changes in operating assets and liabilities . non-cash charges primarily consisted of $ 149.7 million in stock-based compensation expense , $ 66.4 million of amortization of deferred contract acquisition costs , $ 38.7 million of depreciation and amortization , and $ 7.8 million of non-cash operating lease costs . the net cash inflow from changes in operating assets and liabilities was primarily due to a $ 338.8 million increase in deferred revenue , a $ 33.2 million increase in accrued payroll and benefits , a $ 23.8 million increase in accrued expenses and other current liabilities and a $ 11.3 million increase in accounts payable , partially offset by $ 151.0 million increase in deferred contract acquisition costs and a $ 72.5 million increase in accounts receivable . 77 net cash provided by operating activities during fiscal 2020 was $ 99.9 million , which resulted from a net loss of $ 141.8 million , adjusted for non-cash charges of $ 144.3 million and net cash inflow of $ 97.5 million from changes in operating assets and liabilities . non-cash charges primarily consisted of $ 79.9 million in stock-based compensation expense , $ 35.5 million of amortization of deferred contract acquisition costs , $ 23.0 million of depreciation and amortization , and $ 6.0 million due to the change in the fair value of our redeemable convertible preferred stock warrant liability . the net cash inflow from changes in operating assets and liabilities was primarily due to a $ 280.8 million increase in deferred revenue and $ 17.5 million increase in accrued payroll and benefits , partially offset by a $ 86.6 million increase in deferred contract acquisition costs , $ 73.1 million increase in accounts receivable and a $ 43.5 million increase in prepaid expenses and other assets .


 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 presented : replace_table_token_36_th operating activities net cash provided by operating activities during fiscal 2021 was $ 356.6 million , which resulted from a net loss of $ 92.6 million , adjusted for non-cash charges of $ 263.6 million and net cash inflow of $ 185.6 million from changes in operating assets and liabilities . non-cash charges primarily consisted of $ 149.7 million in stock-based compensation expense , $ 66.4 million of amortization of deferred contract acquisition costs , $ 38.7 million of depreciation and amortization , and $ 7.8 million of non-cash operating lease costs . the net cash inflow from changes in operating assets and liabilities was primarily due to a $ 338.8 million increase in deferred revenue , a $ 33.2 million increase in accrued payroll and benefits , a $ 23.8 million increase in accrued expenses and other current liabilities and a $ 11.3 million increase in accounts payable , partially offset by $ 151.0 million increase in deferred contract acquisition costs and a $ 72.5 million increase in accounts receivable . 77 net cash provided by operating activities during fiscal 2020 was $ 99.9 million , which resulted from a net loss of $ 141.8 million , adjusted for non-cash charges of $ 144.3 million and net cash inflow of $ 97.5 million from changes in operating assets and liabilities . non-cash charges primarily consisted of $ 79.9 million in stock-based compensation expense , $ 35.5 million of amortization of deferred contract acquisition costs , $ 23.0 million of depreciation and amortization , and $ 6.0 million due to the change in the fair value of our redeemable convertible preferred stock warrant liability . the net cash inflow from changes in operating assets and liabilities was primarily due to a $ 280.8 million increase in deferred revenue and $ 17.5 million increase in accrued payroll and benefits , partially offset by a $ 86.6 million increase in deferred contract acquisition costs , $ 73.1 million increase in accounts receivable and a $ 43.5 million increase in prepaid expenses and other assets .
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 Suspicious Activity Report : in march 2020 , the world health organization declared the covid-19 outbreak to be a pandemic . since then , the covid-19 pandemic has rapidly spread across the globe and has already resulted in significant volatility , uncertainty , and economic disruption . thus far , the impact of the pandemic has been modest with some customers , particularly in heavily impacted industries , requesting special billing or payment terms . our gross retention rate for the fourth quarter of fiscal 2021 remained consistently high and our dollar-based net retention rate once again exceeded 120 percent as we continued to expand module adoption within new and existing customers . in march 2020 , we implemented several measures to help protect the health and safety of our employees around the globe including restricting all travel and transitioning 100 % of our workforce to be remote . in addition , in response to the uncertain macroeconomic environment , we converted all of our marketable securities to cash and cash equivalents , and as of january 31 , 2021 , all of our investments were classified as cash . 57 we continue to conduct business as usual with modifications to employee travel , employee work locations , customer interactions , and cancellation of certain marketing events , among other things . we will continue to actively monitor the situation and may take further actions that alter our business operations as may be required by federal , state , or local authorities , or that we determine are in the best interests of our employees , customers , partners , suppliers , and stockholders . the extent to which the covid-19 pandemic may impact our longer-term operational and financial performance remains uncertain . furthermore , due to our subscription-based business model , the effect of the covid-19 pandemic may not be fully reflected in our results of operations until future periods , if at all . the extent of the impact of the covid-19 pandemic will depend on several factors , including the pace of reopening the economy around the world ; the possible resurgence in the spread of the virus ; the development cycle of therapeutics and vaccines ; the impact on our customers and our sales cycles ; the impact on our customer , employee , and industry events ; and the effect on our vendors . please see part i , item 1a , “ risk factors ” in this annual report on form 10-k for a further description of the material risks we currently face , including risks related to the covid-19 pandemic . in march 2020 , we launched two initiatives to help our customers quickly onboard new remote workers without sacrificing protection or having to worry about a procurement cycle . this included a surge relief plan that allows our customers to surge the number of endpoints for a limited time . additionally , we launched a falcon prevent for home use program that allows our customers ' company administrators to install falcon prevent on their employees ' home systems . we believe both of these initiatives have been well received by our customers . on september 30 , 2020 , we acquired preempt security , a privately-held delaware corporation that developed real-time access control and threat prevention technology ( the “ acquisition ” ) . the total consideration transferred was $ 91.2 million which consisted of $ 87.4 million in cash and $ 3.8 million representing the fair value of replacement equity awards attributable to pre-acquisition service . the purchase price was allocated , on a preliminary basis , to identified intangible assets , which include developed technology , customer relationships and trade names , of $ 16.4 million , net tangible assets acquired of $ ( 0.5 ) million and goodwill of $ 75.3 million , representing the excess of the purchase price over the fair value of net tangible and intangible assets acquired . with this acquisition , we plan to offer customers enhanced zero trust security capabilities and strengthen our falcon platform with conditional access technology . the addition of preempt security 's technology to the falcon platform will help customers achieve end-to-end visibility and enforcement on identity data . on january 4 , 2021 , we amended and restated our existing credit agreement ( the “ a & r credit agreement ” and the facility thereunder the “ revolving facility ” ) among crowdstrike , inc. , as borrower , crowdstrike holdings , inc. , as guarantor , and silicon valley bank and the other lenders party thereto , providing us with a revolving line of credit of up to $ 750.0 million , including a letter of credit sub-facility in the aggregate amount of $ 100.0 million , and a swingline sub-facility in the aggregate amount of $ 50.0 million . we also have the option to request an incremental facility of up to an additional $ 250.0 million from one or more of the lenders under the a & r credit agreement . the a & r credit agreement is guaranteed by all of our material domestic subsidiaries . the maturity date under the a & r credit agreement is january 2 , 2026. on january 20 , 2021 , we issued and sold $ 750.0 million aggregate principal amount of 3.000 % senior notes due 2029 ( the “ senior notes ” ) . the senior notes are guaranteed by one of our subsidiaries , crowdstrike , inc. , as of the closing date , and thereafter will be guaranteed by any of our domestic subsidiaries that become borrowers or guarantors under our senior secured revolving credit facility . the senior notes and the guarantee are general unsecured senior obligations and rank equal in right of payment to all of our existing and future senior indebtedness . interest will be payable semi-annually at a rate of 3.000 % per year . story_separator_special_tag 62 interest expense : interest expense consists primarily of interest expense on our secured revolving credit facility , interest expense from amortization of debt issuance costs , and contractual interest expense for our senior notes issued in january 2021. we expect interest expense to be higher in fiscal 2022 as a result of the issuance of our senior notes . other income ( expense ) , net . other income ( expense ) , net , consists primarily of income earned on our cash equivalents and marketable securities ; expense related to the fair value of warrants for our redeemable convertible preferred stock and foreign currency transaction gains and losses . provision for income taxes . provision for income taxes consists of federal and state income taxes in the united states and income taxes and withholding taxes related to customer payments in certain foreign jurisdictions in which we conduct business . we maintain a full valuation allowance on our u.s. federal and state and uk deferred tax assets that we have determined are not realizable on a more likely than not basis . results of operations the following tables set forth our consolidated statements of operations in dollar amounts and as a percentage of total revenue for each period presented : replace_table_token_11_th ( 1 ) includes stock-based compensation expense as follows : replace_table_token_12_th 63 ( 2 ) includes amortization of acquired intangible assets as follows : replace_table_token_13_th ( 3 ) includes acquisition-related expenses as follows : year ended january , 31 2021 2020 2019 ( in thousands ) general and administrative $ 3,758 $ — $ — total acquisition-related expenses $ 3,758 $ — $ — ( 4 ) includes amortization of debt issuance costs and discount as follows : replace_table_token_14_th the following table presents the components of our consolidated statements of operations as a percentage of total revenue for the periods presented : replace_table_token_15_th 64 comparison of fiscal 2021 and fiscal 2020 revenue the following shows total revenue from subscriptions and professional services for fiscal 2021 , as compared to fiscal 2020 : replace_table_token_16_th total revenue increased by $ 393.0 million , or 82 % , in fiscal 2021 , compared to fiscal 2020. subscription revenue accounted for 92 % of our total revenue in fiscal 2021 , and 91 % in fiscal 2020. professional services revenue accounted for 8 % of our total revenue in fiscal 2021 and 9 % in fiscal 2020. subscription revenue increased by $ 368.3 million , or 84 % , in fiscal 2021 , compared to fiscal 2020. this increase was primarily attributable to the addition of new subscription customers , as we increased our customer base by 82 % , fro m 5,431 subscription customers in fiscal 2020 to 9,896 subscription customers in fiscal 2021. s ubscription revenue from new customers , subscription revenue from the renewal of existing customers , and subscription revenue from the sale of additional endpoints and additional modules to existing customers accounted for 33 % , 36 % , and 31 % of total subscription revenue in fiscal 2021 , respectively . subscription revenue from new customers , subscription revenue from the renewal of existing customers , and subscription revenue from the sale of additional endpoints and additional modules to existing customers accounted for 40 % , 33 % , and 27 % of total subscription revenue in fiscal 2020 , respectively . professional services revenue increased by $ 24.7 million , or 55 % , in fiscal 2021 , compared to fiscal 2020 , and was primarily attributable to an increase in the number of professional service hours performed . the following shows cost of revenue related to subscriptions and professional services for fiscal 2021 , as compared to fiscal 2020 : replace_table_token_17_th total cost of revenue increased by $ 87.9 million , or 62 % , in fiscal 2021 , compared to fiscal 2020. subscription cost of revenue increased by $ 72.7 million , or 65 % , in fiscal 2021 , compared to fiscal 2020. the increase in subscription cost of revenue was primarily due to an increase in employee-related expenses of $ 27.6 million driven by a 74 % increase in average headcount , an increase in cloud hosting and related services of $ 23.3 million driven by increased customer activity , an increase in depreciation of data center equipment of $ 7.8 million , an increase in stock-based compensation expense of $ 6.5 million , an increase in allocated overhead costs of $ 4.1 million , an increase in the amortization of internal use software of $ 1.6 million , and an increase in employee health insurance expense of $ 1.4 million , partially offset by a $ 1.2 million decrease in travel related costs due to the fact that , as a result of the covid-19 pandemic , a majority of our workforce was working remotely and incurred limited travel costs during fiscal 2021. professional services cost of revenue increased by $ 15.2 million , or 52 % , in fiscal 2021 , compared to fiscal 2020. the increase in professional services cost of revenue was primarily due to an increase in employee-related expenses of $ 11.4 million driven by an increase in average headcount of 47 % and an increase in stock-based compensation expense of $ 3.5 million , partially offset by a $ 1.1 million decrease in travel related costs due to the fact that , as a result of the covid-19 pandemic , a majority of our workforce was working remotely and incurred limited travel costs during fiscal 2021 . 65 the following shows gross profit and gross margin for subscriptions and professional services for fiscal 2021 , as compared to fiscal 2020. replace_table_token_18_th replace_table_token_19_th subscription gross margin increased by 3 % , in fiscal 2021 , compared to fiscal 2020. this increase was a result of continuing to shift more of our operations from third-party cloud service providers to colocation data centers , renegotiating the terms of

