we believe this ability to co-invest will continue to enhance our ability to further our investment objectives and strategies . if we are participating in an investment with one or more co-investors , our investment is likely to be smaller than if we were investing alone . business portfolio and investment activity in general , our investments in debt securities have a term of no more than seven years , accrue interest at variable rates ( generally based on the one-month libor ) and , to a lesser extent , at fixed rates . we seek debt instruments that pay interest monthly or , at a minimum , quarterly , may have a success fee or deferred interest provision and are primarily interest only , with all principal and any accrued but unpaid interest due at maturity . generally , success fees accrue at a set rate and are contractually due upon a change of control of a portfolio company , typically from an exit or sale . some debt securities have deferred interest whereby some portion of the interest payment is added to the principal balance so that the interest is paid , together with the principal , at maturity . this form of deferred interest is often called pik interest . 44 typically , our equity investments consist of common stock , preferred stock , limited liability company interests , or warrants to purchase the foregoing . often , these equity investments occur in connection with our original investment , recapitalizing a business , or refinancing existing debt . during the year ended september 30 , 2018 , we invested $ 67.9 million in ten new portfolio companies and extended $ 38.7 million of investments to existing portfolio companies . in addition , during the year ended september 30 , 2018 , we exited seven portfolio companies through sales and early payoffs . we received a total of $ 66.9 million in combined net proceeds and principal repayments from the aforementioned portfolio company exits as well as existing portfolio companies during the year ended september 30 , 2018. this activity resulted in a net increase in our overall portfolio by three portfolio companies to 50 and a net increase of $ 16.0 million in our portfolio at cost since september 30 , 2017. from our initial public offering in august 2001 through september 30 , 2018 , we have made 495 different loans to , or investments in , 226 companies for a total of approximately $ 1.8 billion , before giving effect to principal repayments on investments and divestitures . during the year ended september 30 , 2018 , the following significant transactions occurred : in october 2017 , we sold our investment in flight fit n fun llc for a realized gain of $ 0.6 million . in connection with the sale , we received net cash proceeds of approximately $ 9.4 million , including the repayment of our debt investment of $ 7.8 million at par . in october 2017 , we invested $ 11.0 million in applied voice & speech technologies , inc. through secured first lien debt . in october 2017 , our investment in psc industrial holdings , llc paid off at par for net cash proceeds of $ 3.5 million . in november 2017 , we invested $ 7.5 million in arc drilling holdings llc through a combination of secured first lien debt and equity . in november 2017 , we invested $ 7.5 million in gray matter systems , llc through secured second lien debt . in march 2018 , we invested an additional $ 3.6 million in gray matter systems , llc , through secured second lien debt . in november 2017 , our investment in datapipe , inc. paid off at par for net cash proceeds of $ 2.0 million . in november 2017 , we invested $ 5.0 million in digicert holdings , inc. through secured second lien debt . in march 2018 , we sold $ 2.0 million of this investment for net cash proceeds of $ 2.0 million . in november 2017 , we invested $ 4.0 million in red ventures , llc through secured second lien debt . in november 2017 , we invested $ 1.0 million in abg intermediate holdings 2 , llc through secured second lien debt . in january 2018 , we sold this investment for net cash proceeds of $ 1.0 million . in december 2017 , we invested $ 20.0 million in impact ! chemical technologies , inc. through secured first lien debt . in january 2018 , we invested $ 8.1 million in xmedius solutions inc. through secured first lien debt . in february 2018 , we invested an additional $ 4.0 million in an existing portfolio company , lignetics , inc. , through secured first lien debt . in march , july and september 2018 , an existing portfolio company , el academies , inc. , drew $ 1.4 million , $ 4.4 million and $ 3.2 million , respectively , on the unused portion of its secured first lien delayed draw term loan . in march 2018 , we sold our $ 1.0 million investment in neustar , inc. for net cash proceeds of $ 1.0 million . 45 in april 2018 , we invested $ 3.0 million in cha holdings , inc. through secured second lien debt . in may 2018 , our investment in taproot partners , inc. paid off , which resulted in prepayment fees of $ 0.5 million and success fee income of $ 0.4 million . in connection with the pay off , we received net cash proceeds of $ 22.9 million , including the repayment of our debt investment of $ 22.0 million at par . in may 2018 , we invested an additional $ 10.0 million in an existing portfolio company , merlin international , inc. , through secured second lien debt . story_separator_special_tag as of september 30 , 2018 , the fair value of our investment portfolio was less than its cost basis by approximately $ 37.4 million and our entire investment portfolio was valued at 91.2 % of cost , as compared to cumulative net unrealized depreciation of $ 59.1 million and a valuation of our entire portfolio at 85.6 % of cost as of september 30 , 2017. this year over year increase in the cumulative unrealized depreciation on investments represents net unrealized appreciation of $ 21.6 million for the year ended september 30 , 2018. the cumulative net unrealized depreciation of our investments does not have an impact on our current ability to pay distributions to stockholders ; however , it may be an indication of future realized losses , which could ultimately reduce our income available for distribution to stockholders . 52 net unrealized ( appreciation ) depreciation of other during the year ended september 30 , 2018 , we recorded $ 0.1 million of unrealized appreciation on our credit facility at fair value as compared to $ 0.1 million of unrealized depreciation during the year ended september 30 , 2017. comparison of the year ended september 30 , 2017 to the year ended september 30 , 2016 replace_table_token_15_th investment income interest income increased by 5.3 % for the year ended september 30 , 2017 , as compared to the prior year . this increase was due primarily to an increase in the weighted average yield on our interest-bearing portfolio . the weighted average yield on our interest-bearing investments is based on the current stated interest rate on interest-bearing investments which increased to 11.6 % for the year ended september 30 , 2017 compared to 11.1 % for the year ended september 30 , 2016 , inclusive of any allowances on interest receivables made during those periods . the weighted average principal balance of our interest-bearing investment portfolio during the year ended september 30 , 2017 , was $ 320.1 million , compared to $ 317.0 million for the prior year , an increase of $ 3.1 million , or 1.0 % . as of september 30 , 2017 , certain loans to two portfolio companies , sunshine and adc , were on non-accrual status , with an aggregate debt cost basis of approximately $ 27.9 million , or 7.5 % of the cost basis of all debt investments in our portfolio . as of september 30 , 2016 , certain loans to two portfolio companies , sunshine and vertellus holdings , llc , were on non-accrual status , with an aggregate debt cost basis of approximately $ 26.5 million , or 7.7 % of the cost basis of all debt investments in our portfolio . 53 other income decreased by 44.5 % during the year ended september 30 , 2017 , as compared to the prior year . this decrease was primarily due to a $ 1.9 million decrease in success fees recognized year over year . for the year ended september 30 , 2017 , other income consisted primarily of $ 1.5 million in success fees recognized , $ 0.3 million in dividend income , and $ 0.3 million in prepayment fees received . for the year ended september 30 , 2016 , other income consisted primarily of $ 3.4 million in success fees recognized , $ 0.3 million in dividend income , and $ 0.2 million in prepayment fees . the following tables list the investment income for our five largest portfolio company investments at fair value during the respective years : replace_table_token_16_th ( a ) new investment during applicable period . expenses expenses , net of credits from the adviser , decreased by 9.3 % for the year ended september 30 , 2017 as compared to the prior year . this decrease was primarily due to decreases in our net base management and incentive fees to the advisor . interest expense increased by 6.0 % during the year ended september 30 , 2017 , as compared to the prior year , due to an increase in the libor component of the effective interest rate partially offset by a lower weighted average balance outstanding . the effective interest rate on our credit facility , excluding the impact of deferred financing costs , was 5.3 % during the year ended september 30 , 2017 compared to 4.5 % during the prior year period . the weighted average balance outstanding on our credit facility during the year ended september 30 , 2017 , was approximately $ 58.4 million , as compared to $ 64.0 million in the prior year period , a decrease of 8.8 % . other expenses decreased by 20.9 % during the year ended september 30 , 2017 , as compared to the prior year , primarily due to decreases in shareholder related costs and professional fees . 54 net base management fee earned by the adviser decreased by $ 0.8 million , or 17.4 % , during the year ended september 30 , 2017 , as compared to the prior year period , resulting from an increase in portfolio company fee credits due to new investments made in the current year period . our board of directors accepted non-contractual , unconditional and irrevocable credits from the adviser to reduce the income-based incentive fee to the extent net investment income did not cover 100.0 % of our distributions to common stockholders during the years ended september 30 , 2017 and 2016 , which credits totaled $ 2.3 million and $ 1.4 million , respectively . the base management , loan servicing and incentive fees , and associated non-contractual , unconditional and irrevocable credits , are computed quarterly , as described under transactions with the adviser in note 4 related party transactions of the accompanying notes to consolidated financial statements and are summarized in the following table : replace_table_token_17_th ( c ) average total assets subject to the base management fee is defined as total assets

liquidity and capital resources operating activities our cash flows from operating activities are primarily generated from the interest payments on debt securities that we receive from our portfolio companies , as well as net proceeds received through repayments or sales of our investments . we utilize this cash primarily to fund new investments , make interest payments on our credit facility , make distributions to our stockholders , pay management and administrative fees to the adviser and administrator , and for other operating expenses . net cash used in operating activities for the year ended september 30 , 2018 was $ 17.6 million as compared to $ 12.9 million for the year ended september 30 , 2017. the change was primarily due to a decrease in principal repayments and net proceeds from sales of investments partially offset by a decrease in purchases of investments year over year . repayments and net proceeds from sales were $ 67.9 million during the year ended september 30 , 2018 compared to $ 83.4 million during the year ended september 30 , 2017. purchase of investments was $ 106.6 million during the year ended september 30 , 2018 , compared to $ 112.1 million during the year ended september 30 , 2017. net cash used in operating activities for the year ended september 30 , 2017 was $ 12.9 million as compared to net cash provided by operating activities of $ 60.0 million for the year ended september 30 , 2016. the change was primarily due to an increase in purchases of investments and a decrease in principal repayments on investments and net proceeds from sale of investments period over period . purchases of investments were $ 112.1 million during the year ended september 30 , 2017 compared to $ 80.0 million during the prior year period .


 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.
     ```liquidity and capital resources operating activities our cash flows from operating activities are primarily generated from the interest payments on debt securities that we receive from our portfolio companies , as well as net proceeds received through repayments or sales of our investments . we utilize this cash primarily to fund new investments , make interest payments on our credit facility , make distributions to our stockholders , pay management and administrative fees to the adviser and administrator , and for other operating expenses . net cash used in operating activities for the year ended september 30 , 2018 was $ 17.6 million as compared to $ 12.9 million for the year ended september 30 , 2017. the change was primarily due to a decrease in principal repayments and net proceeds from sales of investments partially offset by a decrease in purchases of investments year over year . repayments and net proceeds from sales were $ 67.9 million during the year ended september 30 , 2018 compared to $ 83.4 million during the year ended september 30 , 2017. purchase of investments was $ 106.6 million during the year ended september 30 , 2018 , compared to $ 112.1 million during the year ended september 30 , 2017. net cash used in operating activities for the year ended september 30 , 2017 was $ 12.9 million as compared to net cash provided by operating activities of $ 60.0 million for the year ended september 30 , 2016. the change was primarily due to an increase in purchases of investments and a decrease in principal repayments on investments and net proceeds from sale of investments period over period . purchases of investments were $ 112.1 million during the year ended september 30 , 2017 compared to $ 80.0 million during the prior year period .
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 Suspicious Activity Report : we believe this ability to co-invest will continue to enhance our ability to further our investment objectives and strategies . if we are participating in an investment with one or more co-investors , our investment is likely to be smaller than if we were investing alone . business portfolio and investment activity in general , our investments in debt securities have a term of no more than seven years , accrue interest at variable rates ( generally based on the one-month libor ) and , to a lesser extent , at fixed rates . we seek debt instruments that pay interest monthly or , at a minimum , quarterly , may have a success fee or deferred interest provision and are primarily interest only , with all principal and any accrued but unpaid interest due at maturity . generally , success fees accrue at a set rate and are contractually due upon a change of control of a portfolio company , typically from an exit or sale . some debt securities have deferred interest whereby some portion of the interest payment is added to the principal balance so that the interest is paid , together with the principal , at maturity . this form of deferred interest is often called pik interest . 44 typically , our equity investments consist of common stock , preferred stock , limited liability company interests , or warrants to purchase the foregoing . often , these equity investments occur in connection with our original investment , recapitalizing a business , or refinancing existing debt . during the year ended september 30 , 2018 , we invested $ 67.9 million in ten new portfolio companies and extended $ 38.7 million of investments to existing portfolio companies . in addition , during the year ended september 30 , 2018 , we exited seven portfolio companies through sales and early payoffs . we received a total of $ 66.9 million in combined net proceeds and principal repayments from the aforementioned portfolio company exits as well as existing portfolio companies during the year ended september 30 , 2018. this activity resulted in a net increase in our overall portfolio by three portfolio companies to 50 and a net increase of $ 16.0 million in our portfolio at cost since september 30 , 2017. from our initial public offering in august 2001 through september 30 , 2018 , we have made 495 different loans to , or investments in , 226 companies for a total of approximately $ 1.8 billion , before giving effect to principal repayments on investments and divestitures . during the year ended september 30 , 2018 , the following significant transactions occurred : in october 2017 , we sold our investment in flight fit n fun llc for a realized gain of $ 0.6 million . in connection with the sale , we received net cash proceeds of approximately $ 9.4 million , including the repayment of our debt investment of $ 7.8 million at par . in october 2017 , we invested $ 11.0 million in applied voice & speech technologies , inc. through secured first lien debt . in october 2017 , our investment in psc industrial holdings , llc paid off at par for net cash proceeds of $ 3.5 million . in november 2017 , we invested $ 7.5 million in arc drilling holdings llc through a combination of secured first lien debt and equity . in november 2017 , we invested $ 7.5 million in gray matter systems , llc through secured second lien debt . in march 2018 , we invested an additional $ 3.6 million in gray matter systems , llc , through secured second lien debt . in november 2017 , our investment in datapipe , inc. paid off at par for net cash proceeds of $ 2.0 million . in november 2017 , we invested $ 5.0 million in digicert holdings , inc. through secured second lien debt . in march 2018 , we sold $ 2.0 million of this investment for net cash proceeds of $ 2.0 million . in november 2017 , we invested $ 4.0 million in red ventures , llc through secured second lien debt . in november 2017 , we invested $ 1.0 million in abg intermediate holdings 2 , llc through secured second lien debt . in january 2018 , we sold this investment for net cash proceeds of $ 1.0 million . in december 2017 , we invested $ 20.0 million in impact ! chemical technologies , inc. through secured first lien debt . in january 2018 , we invested $ 8.1 million in xmedius solutions inc. through secured first lien debt . in february 2018 , we invested an additional $ 4.0 million in an existing portfolio company , lignetics , inc. , through secured first lien debt . in march , july and september 2018 , an existing portfolio company , el academies , inc. , drew $ 1.4 million , $ 4.4 million and $ 3.2 million , respectively , on the unused portion of its secured first lien delayed draw term loan . in march 2018 , we sold our $ 1.0 million investment in neustar , inc. for net cash proceeds of $ 1.0 million . 45 in april 2018 , we invested $ 3.0 million in cha holdings , inc. through secured second lien debt . in may 2018 , our investment in taproot partners , inc. paid off , which resulted in prepayment fees of $ 0.5 million and success fee income of $ 0.4 million . in connection with the pay off , we received net cash proceeds of $ 22.9 million , including the repayment of our debt investment of $ 22.0 million at par . in may 2018 , we invested an additional $ 10.0 million in an existing portfolio company , merlin international , inc. , through secured second lien debt . story_separator_special_tag as of september 30 , 2018 , the fair value of our investment portfolio was less than its cost basis by approximately $ 37.4 million and our entire investment portfolio was valued at 91.2 % of cost , as compared to cumulative net unrealized depreciation of $ 59.1 million and a valuation of our entire portfolio at 85.6 % of cost as of september 30 , 2017. this year over year increase in the cumulative unrealized depreciation on investments represents net unrealized appreciation of $ 21.6 million for the year ended september 30 , 2018. the cumulative net unrealized depreciation of our investments does not have an impact on our current ability to pay distributions to stockholders ; however , it may be an indication of future realized losses , which could ultimately reduce our income available for distribution to stockholders . 52 net unrealized ( appreciation ) depreciation of other during the year ended september 30 , 2018 , we recorded $ 0.1 million of unrealized appreciation on our credit facility at fair value as compared to $ 0.1 million of unrealized depreciation during the year ended september 30 , 2017. comparison of the year ended september 30 , 2017 to the year ended september 30 , 2016 replace_table_token_15_th investment income interest income increased by 5.3 % for the year ended september 30 , 2017 , as compared to the prior year . this increase was due primarily to an increase in the weighted average yield on our interest-bearing portfolio . the weighted average yield on our interest-bearing investments is based on the current stated interest rate on interest-bearing investments which increased to 11.6 % for the year ended september 30 , 2017 compared to 11.1 % for the year ended september 30 , 2016 , inclusive of any allowances on interest receivables made during those periods . the weighted average principal balance of our interest-bearing investment portfolio during the year ended september 30 , 2017 , was $ 320.1 million , compared to $ 317.0 million for the prior year , an increase of $ 3.1 million , or 1.0 % . as of september 30 , 2017 , certain loans to two portfolio companies , sunshine and adc , were on non-accrual status , with an aggregate debt cost basis of approximately $ 27.9 million , or 7.5 % of the cost basis of all debt investments in our portfolio . as of september 30 , 2016 , certain loans to two portfolio companies , sunshine and vertellus holdings , llc , were on non-accrual status , with an aggregate debt cost basis of approximately $ 26.5 million , or 7.7 % of the cost basis of all debt investments in our portfolio . 53 other income decreased by 44.5 % during the year ended september 30 , 2017 , as compared to the prior year . this decrease was primarily due to a $ 1.9 million decrease in success fees recognized year over year . for the year ended september 30 , 2017 , other income consisted primarily of $ 1.5 million in success fees recognized , $ 0.3 million in dividend income , and $ 0.3 million in prepayment fees received . for the year ended september 30 , 2016 , other income consisted primarily of $ 3.4 million in success fees recognized , $ 0.3 million in dividend income , and $ 0.2 million in prepayment fees . the following tables list the investment income for our five largest portfolio company investments at fair value during the respective years : replace_table_token_16_th ( a ) new investment during applicable period . expenses expenses , net of credits from the adviser , decreased by 9.3 % for the year ended september 30 , 2017 as compared to the prior year . this decrease was primarily due to decreases in our net base management and incentive fees to the advisor . interest expense increased by 6.0 % during the year ended september 30 , 2017 , as compared to the prior year , due to an increase in the libor component of the effective interest rate partially offset by a lower weighted average balance outstanding . the effective interest rate on our credit facility , excluding the impact of deferred financing costs , was 5.3 % during the year ended september 30 , 2017 compared to 4.5 % during the prior year period . the weighted average balance outstanding on our credit facility during the year ended september 30 , 2017 , was approximately $ 58.4 million , as compared to $ 64.0 million in the prior year period , a decrease of 8.8 % . other expenses decreased by 20.9 % during the year ended september 30 , 2017 , as compared to the prior year , primarily due to decreases in shareholder related costs and professional fees . 54 net base management fee earned by the adviser decreased by $ 0.8 million , or 17.4 % , during the year ended september 30 , 2017 , as compared to the prior year period , resulting from an increase in portfolio company fee credits due to new investments made in the current year period . our board of directors accepted non-contractual , unconditional and irrevocable credits from the adviser to reduce the income-based incentive fee to the extent net investment income did not cover 100.0 % of our distributions to common stockholders during the years ended september 30 , 2017 and 2016 , which credits totaled $ 2.3 million and $ 1.4 million , respectively . the base management , loan servicing and incentive fees , and associated non-contractual , unconditional and irrevocable credits , are computed quarterly , as described under transactions with the adviser in note 4 related party transactions of the accompanying notes to consolidated financial statements and are summarized in the following table : replace_table_token_17_th ( c ) average total assets subject to the base management fee is defined as total assets

