our 2017 and 2020 term loans converted to series 1 common stock in connection with the ipo , resulting in a $ 53.9 million reduction of our outstanding long-term debt . on november 12 , 2020 , we completed our secondary offering , in which we issued and sold 1,000,000 shares of our series 1 common stock at $ 68.00 per share . the secondary offering resulted in net proceeds of $ 65.1 million after deducting underwriting discounts , commissions and other offering costs . existing stockholders sold an additional 4,750,000 shares of series 1 common stock , including 750,000 shares of series 1 common stock that were sold pursuant to the exercise in full of the underwriters ' option to purchase additional shares of series 1 common stock at $ 68.00 per share . we did not receive any proceeds from the sale of shares by the selling stockholders in the secondary offering . additionally , upon completion of the secondary offering , we fully repaid approximately $ 22 million of our outstanding indebtedness under our credit facility . key factors affecting our performance we believe our future performance will depend on many factors , including the following : 33 continued growth of ecommerce domestically and globally ecommerce is rapidly transforming global b2c and b2b commerce . b2c ecommerce was nonexistent in the early-1990s and grew to approximately 10 % of all global retail spending in 2017 , according to emarketer . emarketer estimates that it will take just six years for this percentage to more than double to 21 % of global retail spending in 2023. the rapid growth in ecommerce is prompting companies to adopt ecommerce platforms like bigcommerce to create compelling branded ecommerce stores and power cross-channel connections to online marketplaces , social networks , and offline pos systems . we believe we have a substantial opportunity to serve a larger number of customers as ecommerce continues to grow around the world by extending into new and emerging segments within ecommerce . the following segments are significant areas of potential growth and strategic focus for us : headless commerce . this refers to businesses whose technology strategy is to decouple their front-end customer experience technology from their back-end commerce platform . in terms of online strategy , these companies are typically brand- , marketing- , or experience-led . we serve headless use cases better than most of our competitors due to years of investment in our platform apis and integration capabilities . pre-built integrations connect our platform with leading cmss such as acquia , adobe , bloomreach , drupal , sitecore , and wordpress . b2b . as of december 31 , 2020 , approximately 10 % of our customers use bigcommerce primarily for b2b sales . in many cases , these customers ' needs are met using our native functionality , including b2b features like customer groups and price lists . in other cases , these customers complement bigcommerce with purpose-built b2b extensions and applications in the bigcommerce apps marketplace . over time , we intend to add more b2b functionality to both the bigcommerce apps marketplace and our native feature set . large enterprise . increasingly , we are successfully competing for large enterprise sites selling more than $ 50 million annually online , with our enterprise plan product feature set , along with our sales , marketing , solutioning , and service capabilities . efficient acquisition of new customers the growth of our customer base is important to our continued revenue growth . we believe we are positioned to grow significantly through a combination of our own marketing and sales initiatives , customer referrals from our agency and technology partners , and word-of-mouth referrals from existing customers . we measure the efficiency of new customer acquisition by comparing the lifetime value ( “ ltv ” ) of newly-acquired customers to the customer acquisition costs ( “ cac ” ) of the associated time period to get an “ ltv : cac ratio . ” we calculate ltv as gross profit from new sales during the four quarters of any given year divided by the estimated future subscription churn rate . we calculate cac as total sales and marketing expense incurred during the associated preceding four quarters . new smb , mid-market and enterprise customers were added at an estimated ltv to cac ratio of 4.9:1 , up from 4.4:1 in 2019. retention and growth of our existing customers we believe our long-term revenue growth is correlated with the growth of our existing customers ' ecommerce businesses . we strive to maintain industry-leading service levels and platform capabilities to maximize customer success and retention . our revenue grows with that of our customers . as they generate more online sales , we generate more subscription revenue through automated sales-based upgrades on our essentials plans and order adjustments on our enterprise plans . typical enterprise contracts have terms ranging from 12 to 36 months and do not include the ability to terminate for convenience . as our customers ' online sales increase , our partner and services revenue generated by revenue-sharing agreements with our strategic technology partners increases as well . our ability to retain and grow our customers ' ecommerce businesses often depends on the continued expansion of our platform and the capabilities of our strategic technology partners to provide revenue generating services to our customers . we continually evaluate prospective and existing partners ' abilities to enhance the capabilities of our customers ' ecommerce businesses . we add new partners and expand existing partner relationships to enhance the utility of our platform , while creating new opportunities to expand our revenue share in partner and services revenue . as we continue to grow as a platform , we believe our ability to realize more favorable and expansive revenue share agreements will grow as well . we also grow by selling additional stores to existing customers . story_separator_special_tag revenue increased $ 20.2 million , or 22 % , to $ 112.1 million in 2019 from $ 91.9 million in 2018 , as a result of increases in both subscription solutions and partner and services revenue . subscription solutions revenue increased $ 12.2 million , or 17.3 % , to $ 82.7 million in 2019 from $ 70.5 million in 2018 , primarily due to the increase in mid-market and large enterprise customers and our international expansion efforts . partner and services revenue increased $ 8.0 million , or 37.6 % , to $ 29.4 million in 2019 from $ 21.4 million in 2018 , primarily as a result of increases in revenue-sharing activity with our technology partners . cost of revenue , gross profit , and gross margin the following table presents our cost of revenue , gross profit , and gross margin for each of the periods indicated : replace_table_token_12_th cost of revenue increased $ 7.1 million , or 26.3 % , to $ 34.1 million for the year ended december 31 , 2020 from $ 27.0 million for the year ended december 31 , 2019 , primarily as a result of higher hosting costs of $ 2.4 million as a result of increased transactions processed and higher personnel costs of $ 4.5 million , including stock-based compensation expense . gross margin increased to 77.6 % during the year ended december 31 , 2020 from 75.9 % during the year ended december 31 , 2019. cost of revenue increased $ 5.1 million , or 23.2 % , to $ 27.0 million in 2019 from $ 21.9 million in 2018 , primarily as a result of higher hosting costs of $ 1.3 million as a result of increased transactions processed and increases in personnel-related costs of $ 3.6 million , including stock-based compensation expense , for personnel involved in providing customer support and professional services . headcount for such personnel as of december 31 , 2019 was 180 compared to 145 as of december 31 , 2018. gross margin decreased to 75.9 % during 2019 from 76.1 % during 2018 . 39 operating expenses the following tables present our operating expenses for each of the periods indicated : sales and marketing replace_table_token_13_th sales and marketing expenses increased $ 11.7 million , or 19.3 % , to $ 72.5 million for the year ended december 31 , 2020 from $ 60.7 million for the year ended december 31 , 2019 , primarily due to higher staffing costs of $ 13.7 million , including stock-based compensation expense and bonuses , offset by a reduction in travel and marketing related expenditures of $ 2.4 million due to shifts in event timing due to the covid-19 pandemic . as a percentage of total revenue , sales and marketing expenses decreased to 47.6 % during the year ended december 31 , 2020 from 54.2 % during the year ended december 31 , 2019 , primarily due to increased operating leverage from revenue growth . sales and marketing expenses increased $ 14.8 million , or 32.3 % , to $ 60.7 million in 2019 from $ 45.9 million in 2018 , primarily due to an increase of $ 11.1 million in personnel-related costs , including stock-based compensation expense , for personnel engaged in acquiring new customers and marketing our products and services . total sales and marketing headcount as of december 31 , 2019 was 181 compared to 155 as of december 31 , 2018. the increase was also attributed to a $ 3.3 million increase in marketing program spend to continue the promotion of our products and services globally . as a percentage of total revenue , sales and marketing expenses increased to 54.2 % during 2019 from 50.0 % during 2018 , primarily due to investments in sales and marketing teams in london , uk and sydney , australia . research and development replace_table_token_14_th research and development expenses increased $ 5.2 million , or 12.1 % , to $ 48.3 million for the year ended december 31 , 2020 from $ 43.1 million for the year ended december 31 , 2019 , primarily due to higher staffing costs of $ 5.4 million including stock-based compensation and bonuses , however declined as a percentage of revenue . this decline reflects our leverage of previous enhancements to our platform capabilities and prior development of new product offerings . research and development expenses were relatively unchanged in absolute dollars for the year ended december 31 , 2019 compared to december 31 , 2018 , however declined as a percentage of revenue , which is reflective of our efforts to leverage the previous enhancements to our platform capabilities and prior development of new product offerings . by opening and expanding an engineering center in kyiv , ukraine in 2019 , we increased our lower-cost development capacity , further driving leverage in research and development spend as a percentage of revenue . total research and development headcount as of december 31 , 2019 was 190 compared to 191 as of december 31 , 2018. general and administrative replace_table_token_15_th general and administrative expenses increased $ 13.9 million , or 62.7 % , to $ 36.1 million for the year ended december 31 , 2020 from $ 22.2 million for the year ended december 31 , 2019. the increase was primarily due to increased staffing costs of $ 11.0 million , including stock-based compensation expense and bonuses , and additional public company compliance costs including , but not limited to director and officer insurance amounting to $ 2.3 million . general and administrative expenses increased $ 2.7 million , or 13.9 % , to $ 22.2 million in 2019 from $ 19.5 million in 2018. the increase was primarily due to an increase of $ 2.4 million in personnel-related expense , including stock-based compensation expense , resulting from the hiring of 40 additional general and administrative personnel . total general and administrative headcount as of december 31 , 2019

cash flows the following table sets forth a summary of our cash flows for the periods indicated . replace_table_token_16_th as of december 31 , 2020 , we had $ 220.6 million in cash , cash equivalents , and restricted cash , an increase of $ 211.4 million compared to $ 9.2 million in 2019. cash and cash equivalents consist of highly-liquid investments with original maturities of less than three months . restricted cash consists of security deposits for future chargebacks and amounts on deposit with certain financial institutions . we maintain cash account balances in excess of fdic-insured limits . operating activities net cash used in operating activities for the years ended december 31 , 2020 , 2019 and 2018 was $ 26.5 million , $ 40.0 million and $ 30.6 million , respectively . this consisted primarily of our net losses adjusted for certain non-cash items including depreciation and amortization , stock-based compensation , debt discount amortization , bad debt expense , and the effect of changes in working capital . investing activities net cash used in investing activities during the year ended december 31 , 2020 was $ 2.0 million . it consisted primarily of purchases of property and equipment of $ 2.0 million . net cash provided by investing activities during the year ended december 31 , 2019 was $ 17.9 million . it consisted primarily of proceeds from the sale and maturity of marketable securities of $ 23.5 million , partially offset by purchases of property and equipment of $ 5.6 million . net cash used in investing activities during the year ended december 31 , 2018 was $ 26.5 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 flows the following table sets forth a summary of our cash flows for the periods indicated . replace_table_token_16_th as of december 31 , 2020 , we had $ 220.6 million in cash , cash equivalents , and restricted cash , an increase of $ 211.4 million compared to $ 9.2 million in 2019. cash and cash equivalents consist of highly-liquid investments with original maturities of less than three months . restricted cash consists of security deposits for future chargebacks and amounts on deposit with certain financial institutions . we maintain cash account balances in excess of fdic-insured limits . operating activities net cash used in operating activities for the years ended december 31 , 2020 , 2019 and 2018 was $ 26.5 million , $ 40.0 million and $ 30.6 million , respectively . this consisted primarily of our net losses adjusted for certain non-cash items including depreciation and amortization , stock-based compensation , debt discount amortization , bad debt expense , and the effect of changes in working capital . investing activities net cash used in investing activities during the year ended december 31 , 2020 was $ 2.0 million . it consisted primarily of purchases of property and equipment of $ 2.0 million . net cash provided by investing activities during the year ended december 31 , 2019 was $ 17.9 million . it consisted primarily of proceeds from the sale and maturity of marketable securities of $ 23.5 million , partially offset by purchases of property and equipment of $ 5.6 million . net cash used in investing activities during the year ended december 31 , 2018 was $ 26.5 million .
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 Suspicious Activity Report : our 2017 and 2020 term loans converted to series 1 common stock in connection with the ipo , resulting in a $ 53.9 million reduction of our outstanding long-term debt . on november 12 , 2020 , we completed our secondary offering , in which we issued and sold 1,000,000 shares of our series 1 common stock at $ 68.00 per share . the secondary offering resulted in net proceeds of $ 65.1 million after deducting underwriting discounts , commissions and other offering costs . existing stockholders sold an additional 4,750,000 shares of series 1 common stock , including 750,000 shares of series 1 common stock that were sold pursuant to the exercise in full of the underwriters ' option to purchase additional shares of series 1 common stock at $ 68.00 per share . we did not receive any proceeds from the sale of shares by the selling stockholders in the secondary offering . additionally , upon completion of the secondary offering , we fully repaid approximately $ 22 million of our outstanding indebtedness under our credit facility . key factors affecting our performance we believe our future performance will depend on many factors , including the following : 33 continued growth of ecommerce domestically and globally ecommerce is rapidly transforming global b2c and b2b commerce . b2c ecommerce was nonexistent in the early-1990s and grew to approximately 10 % of all global retail spending in 2017 , according to emarketer . emarketer estimates that it will take just six years for this percentage to more than double to 21 % of global retail spending in 2023. the rapid growth in ecommerce is prompting companies to adopt ecommerce platforms like bigcommerce to create compelling branded ecommerce stores and power cross-channel connections to online marketplaces , social networks , and offline pos systems . we believe we have a substantial opportunity to serve a larger number of customers as ecommerce continues to grow around the world by extending into new and emerging segments within ecommerce . the following segments are significant areas of potential growth and strategic focus for us : headless commerce . this refers to businesses whose technology strategy is to decouple their front-end customer experience technology from their back-end commerce platform . in terms of online strategy , these companies are typically brand- , marketing- , or experience-led . we serve headless use cases better than most of our competitors due to years of investment in our platform apis and integration capabilities . pre-built integrations connect our platform with leading cmss such as acquia , adobe , bloomreach , drupal , sitecore , and wordpress . b2b . as of december 31 , 2020 , approximately 10 % of our customers use bigcommerce primarily for b2b sales . in many cases , these customers ' needs are met using our native functionality , including b2b features like customer groups and price lists . in other cases , these customers complement bigcommerce with purpose-built b2b extensions and applications in the bigcommerce apps marketplace . over time , we intend to add more b2b functionality to both the bigcommerce apps marketplace and our native feature set . large enterprise . increasingly , we are successfully competing for large enterprise sites selling more than $ 50 million annually online , with our enterprise plan product feature set , along with our sales , marketing , solutioning , and service capabilities . efficient acquisition of new customers the growth of our customer base is important to our continued revenue growth . we believe we are positioned to grow significantly through a combination of our own marketing and sales initiatives , customer referrals from our agency and technology partners , and word-of-mouth referrals from existing customers . we measure the efficiency of new customer acquisition by comparing the lifetime value ( “ ltv ” ) of newly-acquired customers to the customer acquisition costs ( “ cac ” ) of the associated time period to get an “ ltv : cac ratio . ” we calculate ltv as gross profit from new sales during the four quarters of any given year divided by the estimated future subscription churn rate . we calculate cac as total sales and marketing expense incurred during the associated preceding four quarters . new smb , mid-market and enterprise customers were added at an estimated ltv to cac ratio of 4.9:1 , up from 4.4:1 in 2019. retention and growth of our existing customers we believe our long-term revenue growth is correlated with the growth of our existing customers ' ecommerce businesses . we strive to maintain industry-leading service levels and platform capabilities to maximize customer success and retention . our revenue grows with that of our customers . as they generate more online sales , we generate more subscription revenue through automated sales-based upgrades on our essentials plans and order adjustments on our enterprise plans . typical enterprise contracts have terms ranging from 12 to 36 months and do not include the ability to terminate for convenience . as our customers ' online sales increase , our partner and services revenue generated by revenue-sharing agreements with our strategic technology partners increases as well . our ability to retain and grow our customers ' ecommerce businesses often depends on the continued expansion of our platform and the capabilities of our strategic technology partners to provide revenue generating services to our customers . we continually evaluate prospective and existing partners ' abilities to enhance the capabilities of our customers ' ecommerce businesses . we add new partners and expand existing partner relationships to enhance the utility of our platform , while creating new opportunities to expand our revenue share in partner and services revenue . as we continue to grow as a platform , we believe our ability to realize more favorable and expansive revenue share agreements will grow as well . we also grow by selling additional stores to existing customers . story_separator_special_tag revenue increased $ 20.2 million , or 22 % , to $ 112.1 million in 2019 from $ 91.9 million in 2018 , as a result of increases in both subscription solutions and partner and services revenue . subscription solutions revenue increased $ 12.2 million , or 17.3 % , to $ 82.7 million in 2019 from $ 70.5 million in 2018 , primarily due to the increase in mid-market and large enterprise customers and our international expansion efforts . partner and services revenue increased $ 8.0 million , or 37.6 % , to $ 29.4 million in 2019 from $ 21.4 million in 2018 , primarily as a result of increases in revenue-sharing activity with our technology partners . cost of revenue , gross profit , and gross margin the following table presents our cost of revenue , gross profit , and gross margin for each of the periods indicated : replace_table_token_12_th cost of revenue increased $ 7.1 million , or 26.3 % , to $ 34.1 million for the year ended december 31 , 2020 from $ 27.0 million for the year ended december 31 , 2019 , primarily as a result of higher hosting costs of $ 2.4 million as a result of increased transactions processed and higher personnel costs of $ 4.5 million , including stock-based compensation expense . gross margin increased to 77.6 % during the year ended december 31 , 2020 from 75.9 % during the year ended december 31 , 2019. cost of revenue increased $ 5.1 million , or 23.2 % , to $ 27.0 million in 2019 from $ 21.9 million in 2018 , primarily as a result of higher hosting costs of $ 1.3 million as a result of increased transactions processed and increases in personnel-related costs of $ 3.6 million , including stock-based compensation expense , for personnel involved in providing customer support and professional services . headcount for such personnel as of december 31 , 2019 was 180 compared to 145 as of december 31 , 2018. gross margin decreased to 75.9 % during 2019 from 76.1 % during 2018 . 39 operating expenses the following tables present our operating expenses for each of the periods indicated : sales and marketing replace_table_token_13_th sales and marketing expenses increased $ 11.7 million , or 19.3 % , to $ 72.5 million for the year ended december 31 , 2020 from $ 60.7 million for the year ended december 31 , 2019 , primarily due to higher staffing costs of $ 13.7 million , including stock-based compensation expense and bonuses , offset by a reduction in travel and marketing related expenditures of $ 2.4 million due to shifts in event timing due to the covid-19 pandemic . as a percentage of total revenue , sales and marketing expenses decreased to 47.6 % during the year ended december 31 , 2020 from 54.2 % during the year ended december 31 , 2019 , primarily due to increased operating leverage from revenue growth . sales and marketing expenses increased $ 14.8 million , or 32.3 % , to $ 60.7 million in 2019 from $ 45.9 million in 2018 , primarily due to an increase of $ 11.1 million in personnel-related costs , including stock-based compensation expense , for personnel engaged in acquiring new customers and marketing our products and services . total sales and marketing headcount as of december 31 , 2019 was 181 compared to 155 as of december 31 , 2018. the increase was also attributed to a $ 3.3 million increase in marketing program spend to continue the promotion of our products and services globally . as a percentage of total revenue , sales and marketing expenses increased to 54.2 % during 2019 from 50.0 % during 2018 , primarily due to investments in sales and marketing teams in london , uk and sydney , australia . research and development replace_table_token_14_th research and development expenses increased $ 5.2 million , or 12.1 % , to $ 48.3 million for the year ended december 31 , 2020 from $ 43.1 million for the year ended december 31 , 2019 , primarily due to higher staffing costs of $ 5.4 million including stock-based compensation and bonuses , however declined as a percentage of revenue . this decline reflects our leverage of previous enhancements to our platform capabilities and prior development of new product offerings . research and development expenses were relatively unchanged in absolute dollars for the year ended december 31 , 2019 compared to december 31 , 2018 , however declined as a percentage of revenue , which is reflective of our efforts to leverage the previous enhancements to our platform capabilities and prior development of new product offerings . by opening and expanding an engineering center in kyiv , ukraine in 2019 , we increased our lower-cost development capacity , further driving leverage in research and development spend as a percentage of revenue . total research and development headcount as of december 31 , 2019 was 190 compared to 191 as of december 31 , 2018. general and administrative replace_table_token_15_th general and administrative expenses increased $ 13.9 million , or 62.7 % , to $ 36.1 million for the year ended december 31 , 2020 from $ 22.2 million for the year ended december 31 , 2019. the increase was primarily due to increased staffing costs of $ 11.0 million , including stock-based compensation expense and bonuses , and additional public company compliance costs including , but not limited to director and officer insurance amounting to $ 2.3 million . general and administrative expenses increased $ 2.7 million , or 13.9 % , to $ 22.2 million in 2019 from $ 19.5 million in 2018. the increase was primarily due to an increase of $ 2.4 million in personnel-related expense , including stock-based compensation expense , resulting from the hiring of 40 additional general and administrative personnel . total general and administrative headcount as of december 31 , 2019

