NASDAQ: GBDC

In this Annual Report on Form 10-K, the term “middle-market” generally refers to companies having earnings before interest, taxes, depreciation and amortization, or EBITDA, of less than $100.0 million annually.

Our investment objective is to generate current income and capital appreciation by investing primarily in senior secured and one stop loans of U.S. middle-market companies. We also selectively invest in second lien and subordinated (a loan that ranks senior only to a borrower's equity securities and ranks junior to all of such borrower's other indebtedness in priority of payment) loans of, and warrants and minority equity securities in, middle-market companies. We intend to achieve our investment objective by (1) accessing the established loan origination channels developed by Golub Capital, a leading lender to middle-market companies that had over $85.0 billion of capital under management as of October 1, 2025, (2) selecting investments within our core middle-market company focus, (3) partnering with experienced private equity firms, or sponsors, in many cases with whom Golub Capital has invested alongside in the past, (4) implementing the disciplined underwriting standards of Golub Capital and (5) drawing upon the aggregate experience and resources of Golub Capital.

We seek to create a portfolio that includes primarily senior secured and one stop loans by primarily investing approximately $10.0 million to $80.0 million of capital, on average, in the securities of middle-market companies. We expect to selectively invest more than $80.0 million in some of our portfolio companies and generally expect that the size of our individual investments will vary proportionately with the size of our capital base.

We generally invest in securities that have been rated below investment grade by independent rating agencies or that would be rated below investment grade if they were rated. These securities, which are often referred to as “junk,” have predominantly speculative characteristics with respect to the issuer’s capacity to pay interest and repay principal. In addition, many of our debt investments have floating interest rates that reset on a periodic basis and typically do not fully pay down principal prior to maturity, which could increase our risk of losing part or all of our investment.

Information Available

Our address is 200 Park Avenue, 25th Floor, New York, NY 10166. Our phone number is (212) 750-6060, and our internet address is www.golubcapitalbdc.com. We make available, free of charge, on our website our proxy statement, Annual Report on Form 10-K, Quarterly Reports on Form 10-Q, current reports on Form 8-K and amendments to those reports as soon as reasonably practicable after we electronically file such material with, or furnish it to, the U.S. Securities and Exchange Commission, or SEC. Information contained on our website is not incorporated by reference into this annual report on Form 10-K and you should not consider information contained on our website to be part of this annual report on Form 10-K or any other report we file with the SEC.

The SEC also maintains a website that contains reports, proxy and information statements and other information we file with the SEC at www.sec.gov. Copies of these reports, proxy and information statements and other information may also be obtained, after paying a duplicating fee, by electronic request at publicinfo@sec.gov.

Our Adviser

Our investment activities are managed by our investment adviser, GC Advisors. GC Advisors is responsible for sourcing potential investments, conducting research and due diligence on prospective investments and equity sponsors, analyzing investment opportunities, structuring our investments and monitoring our investments and portfolio companies on an ongoing basis. GC Advisors was organized in September 2008 and is a registered investment adviser under the Investment Advisers Act of 1940, as amended, or the Advisers Act. Under our amended and restated investment advisory agreement, or the Investment Advisory Agreement, with GC Advisors, we pay GC Advisors a base management fee and an incentive fee for its services. See “Business — Management Agreements — Management Fee” for a discussion of the base management fee and incentive fee, including the cumulative income incentive fee and the income and capital gains incentive fee, payable by us to GC Advisors. Unlike most closed-end funds whose fees are based on assets net of leverage, our base management fee is based on our average-adjusted gross assets (including leverage but adjusted to exclude cash and cash equivalents so that investors do not pay the base management fee on such assets) and, therefore, GC Advisors benefits when we incur debt or use leverage. For purposes of the Investment Advisory Agreement, cash equivalents means U.S. government securities and commercial paper instruments maturing within 270 days of purchase. Additionally, under the incentive fee structure, GC Advisors benefits when capital gains are recognized and, because it determines when a holding is sold, GC Advisors controls the timing of the recognition of capital gains. Our board of directors is charged with protecting our interests by monitoring how GC Advisors addresses these and other conflicts of interest associated with its management services and compensation. While not expected to review or approve each borrowing, our independent directors periodically review GC Advisors’ services and fees as well as its portfolio management decisions and portfolio performance. In connection with these reviews, our independent directors consider whether our fees and expenses (including those related to leverage) remain appropriate. See “Business — Management Agreements — Board Approval of the Investment Advisory Agreement.”

GC Advisors is an affiliate of Golub Capital and pursuant to a staffing agreement, or the Staffing Agreement, Golub Capital LLC makes experienced investment professionals available to GC Advisors and provides access to the senior investment personnel of Golub Capital LLC and its affiliates. The Staffing Agreement provides GC Advisors with access to deal flow generated by Golub Capital LLC and its affiliates in the ordinary course of their businesses and commits the members of GC Advisors’ investment committee to serve in that capacity. As our investment adviser, GC Advisors is obligated to allocate investment opportunities among us and its other clients fairly and equitably over time in accordance with its allocation policy. See “Management’s Discussion and Analysis of Financial Condition and Results of Operations — Related Party Transactions.” However, there can be no assurance that such opportunities will be allocated to us fairly or equitably in the short-term or over time. GC Advisors seeks to capitalize on the significant deal origination, credit underwriting, due diligence, investment structuring, execution, portfolio management and monitoring experience of Golub Capital LLC’s investment professionals.

Our Administrator

Golub Capital LLC, our Administrator and an affiliate of GC Advisors, provides the administrative services necessary for us to operate. See “Business — Management Agreements — Administration Agreement” for a discussion of the fees and expenses (subject to the review and approval of our independent directors) we are required to reimburse to the Administrator.

About Golub Capital

Golub Capital, founded in 1994, is a leading lender to middle-market companies, with a long track record of investing in senior secured, one stop, second lien and subordinated loans. As of October 1, 2025, Golub Capital had over $85.0 billion of capital under management. Since its inception, Golub Capital has closed deals with over 420 middle-market sponsors and repeat transactions with over 280 sponsors.

Golub Capital’s middle-market lending group is managed by an eight-member senior management team consisting of Lawrence E. Golub, David B. Golub, Andrew H. Steuerman, Gregory W. Cashman, Spyro G. Alexopoulos, Marc C. Robinson, Robert G. Tuchscherer and Jason J. Van Dussen. As of September 30, 2025, Golub Capital had more than 230 investment professionals supported by more than 800 administrative and back office personnel that focus on operations, finance, legal and compliance, accounting and reporting, marketing, information technology and office management.

Market Trends

We have identified the following trends that could affect our business:

Target Market. We believe that small and middle market companies in the United States with annual revenues between $10 million and $2.5 billion represent a significant growth segment of the U.S. economy and often require substantial capital investments to grow. Middle market companies have generated a significant number of investment opportunities for investment funds managed or advised by Golub Capital, and we believe that this market segment will continue to produce significant investment opportunities for us. We continue to focus our portfolio on borrowers in what we believe are recession resistant industries that are insulated from the effects of economic disruptions.

Specialized Lending Requirements. We believe that several factors render many U.S. financial institutions ill-suited to lend to U.S. middle market companies. For example, based on the experience of our management team, lending to U.S. middle market companies (1) is generally more labor intensive than lending to larger companies due to the smaller size of each investment and the fragmented nature of information for such companies, (2) requires due diligence and underwriting practices consistent with the demands and economic limitations of the middle market and (3) also requires more extensive ongoing monitoring by the lender.

Demand for Debt Capital. We believe there is a large pool of committed but uninvested private equity capital for middle market companies. We expect private equity firms will seek to leverage their investments by combining equity capital with senior secured loans and subordinated debt from other sources, such as us.

Competition from Bank Lenders. We believe that many traditional bank lenders to middle market businesses have either exited or de-emphasized their service and product offerings in the middle market. These traditional lenders have instead focused on lending and providing other services to large corporate clients. We believe this has resulted in fewer key players and the reduced availability of debt capital to the companies we target.

Market Environment: We believe middle market investments are likely to excel in uncertain market environments and that these investments have historically generated premium yields with more desirable structures for lenders as compared to large corporate loans.(1) In addition, we believe the recent credit market dislocation will accelerate the market share shift toward well-positioned larger platforms. On the other hand, we believe that there has been increased competition for direct lending to middle market businesses, which would be expected to result in less favorable pricing terms for our potential investments. If we match our competitors’ pricing, terms and structure, we would expect to experience decreased net interest income, lower yields and increased risk of credit loss. However, we believe that Golub Capital’s scale, product suite, entrenched relationships and strong market position will continue to allow us to find investment opportunities with attractive risk-adjusted returns.

(1) PitchBook LCD, “High-End Middle Market Lending Review Q4 2024” – New-issue first-lien yield-to-maturity. Middle-Market loans have, on average, generated higher yields in comparison to large corporate loans based on data starting in January 2000.

Competitive Strengths

Deep, Experienced Management Team. We are managed by GC Advisors, which has access through the Staffing Agreement to the resources and expertise of Golub Capital’s more than 1,000 employees, led by Lawrence E. Golub, chief executive officer of GC Advisors and an interested director of Golub Capital BDC, and David B. Golub, our chairman, president and chief executive officer. As of September 30, 2025, Golub Capital’s more than 230 investment professionals had an average of approximately 13 years of investment experience and were supported by more than 800 administrative and back office personnel that focus on operations, finance, legal and compliance, accounting and reporting, marketing, information technology and office management. GC Advisors also manages (i) Golub Capital Direct Lending Corporation, a Maryland corporation, or GDLC; (ii) Golub Capital BDC 4, Inc., a Maryland corporation, or GBDC4; (iii) Golub Capital Direct Lending Unlevered Corporation, a Maryland corporation, or GDLCU; and (iv) Golub Capital Private Credit Fund, a Delaware statutory trust, or GCRED, each of which has elected to be regulated as a business development company, have investment mandates similar to ours, and primarily focus on investing in one stop and other senior secured loans. Golub Capital seeks to hire and retain high-quality investment professionals and reward those personnel based on investor returns.

Leading U.S. Debt Platform Provides Access to Proprietary Relationship-Based Deal Flow. GC Advisors gives us access to the deal flow of Golub Capital, one of the leading middle-market lenders in the United States. Golub Capital has been a top 3 Traditional Middle-Market Bookrunner each year from 2008 through Q2 2025 for senior secured loans of up to $500.0 million for leveraged buyouts ranked by number of deals completed, based on London Stock Exchange Group (“LSEG”) Data & Analytics and Golub Capital internal data. We believe this market position makes Golub Capital the first choice lender to many sponsors. Since its inception, Golub Capital has closed deals with over 420 middle-market sponsors and repeat transactions with over 280 sponsors. We believe that Golub Capital receives relationship-based “early looks” and “last looks” at many investment opportunities in the U.S. middle-market market, allowing it to be highly selective in the transactions it pursues.

Disciplined Investment and Underwriting Process. GC Advisors utilizes the established investment process of Golub Capital for reviewing lending opportunities, structuring transactions and monitoring investments. Using its disciplined approach to lending, GC Advisors seeks to minimize credit losses through effective underwriting, comprehensive due diligence investigations, structuring and the implementation of restrictive debt covenants. We expect that GC Advisors will continue to select borrowers whose businesses will retain significant value, even in a depressed market or a distressed sale. GC Advisors intends to reduce risk further by focusing on repeat transactions with proven, successful sponsors. While emphasizing thorough credit analysis, GC Advisors intends to maintain strong relationships with sponsors by offering rapid initial feedback from senior investment professionals on each investment opportunity.

Regimented Credit Monitoring. Following each investment, GC Advisors implements a regimented credit monitoring system. This careful approach, which involves ongoing review and analysis by teams of professionals, has enabled GC Advisors to identify problems early and to assist borrowers before they face difficult liquidity constraints. If necessary, GC Advisors can assume the role of deal sponsor in a work-out situation and has extensive restructuring experience, both in and out of bankruptcy. GC Advisors believes in the need to prepare for possible negative contingencies in order to address them promptly should they arise.

Concentrated Middle-Market Focus. Because of our focus on the middle-market, we understand the following general characteristics of middle-market lending:

•middle-market companies are generally less leveraged than large companies and, we believe, offer more attractive investment returns in the form of upfront fees, prepayment penalties and higher interest rates;

•middle-market issuers are more likely to have simple capital structures;

•carefully structured covenant packages enable middle-market lenders to take early action to remediate poor financial performance; and

•middle-market lenders can undertake thorough due diligence investigations prior to investment.

Investment Criteria/Guidelines

Our investment objective is to generate current income and capital appreciation by investing primarily in senior secured and one stop loans to U.S. middle-market companies in industries we believe are resistant to recessions. We seek to generate strong risk-adjusted net returns by assembling a portfolio of investments across a broad range of industries and private equity investors.

We primarily target U.S. middle-market companies controlled by private equity investors that require capital for growth, acquisitions, recapitalizations, refinancings and leveraged buyouts. We seek to have a portfolio of first-lien, senior secured loans to borrowers focused on a number of sectors and industries that we believe have shown resilience during economic disruptions and are likely to show resilience in future recessionary periods, including, for example, software and technology companies as well as business, financial and healthcare services among others. We also make opportunistic loans to independently owned and publicly held middle market companies. We seek to partner with strong management teams executing long-term growth strategies. Target businesses will typically exhibit some or all of the following characteristics:

•annual EBITDA of less than $100.0 million;

•sustainable leading positions in their respective markets;

•scalable revenues and operating cash flow;

•experienced management teams with successful track records;

•insulation from the effects of economic disruptions;

•stable, predictable cash flows with low technology and market risks;

•a substantial equity cushion in the form of capital ranking junior to our investment provided by a middle market private equity sponsor;

•low capital expenditures requirements;

•a North American base of operations;

•strong customer relationships;

•products, services or distribution channels having distinctive competitive advantages;

•defensible niche strategy or other barriers to entry; and

•demonstrated growth strategies.

While we believe that the criteria listed above are important in identifying and investing in prospective portfolio companies, not all of these criteria will be met by each prospective portfolio company.

Investment Process Overview

We view our investment process as consisting of four distinct phases described below:

Origination. GC Advisors sources investment opportunities through access to a network of over 36,000 individual contacts developed in the financial services and related industries by Golub Capital and managed through a proprietary customer relationship database. Among these contacts is an extensive network of private equity firms and relationships with leading middle-market senior lenders. The senior deal professionals of Golub Capital supplement these leads through personal visits and marketing campaigns. It is their responsibility to identify specific opportunities, to refine opportunities through candid exploration of the underlying facts and circumstances and to apply creative and flexible thinking to solve clients’ financing needs. The investment professionals of Golub Capital have a long and successful track record investing in companies across many industry sectors. Collectively, these investment professionals have closed investments in over 2,700 loans/transactions at Golub Capital. Golub Capital’s investments have been made in the following industries, among others: healthcare, restaurant and retail, software, digital and technology services, specialty manufacturing, business services, consumer products and services, food and beverages, aerospace and defense and value-added distribution.

Golub Capital has principal lending offices in North America, Europe, Asia and the Middle East. Each of Golub Capital’s originators maintains long-standing customer relationships and is responsible for covering a specified target market. We believe those originators’ strength and breadth of relationships across a wide range of markets generate numerous financing opportunities, which we believe enables GC Advisors to be highly selective in recommending investments to us.

Underwriting. We utilize the systematic, consistent approach to underwriting developed by Golub Capital, with a particular focus on determining the value of a business in a downside scenario. The key criteria that we consider include (1) strong and resilient underlying business fundamentals, (2) a substantial equity cushion in the form of capital ranking junior in right of payment to our investment and (3) a conclusion that overall “downside” risk is manageable. While the size of this equity cushion will vary over time and across industries, the equity cushion generally sought by GC Advisors today is between 35% and 45% of total portfolio capitalization. We generally focus on the criteria developed by Golub Capital for evaluating prospective portfolio companies, which uses a combination of analyses, including (1) fundamental analysis of a business’s financial statements, health, management, competitive advantages, competitors and markets; (2) analysis of opportunities in a given market based upon fluctuations due to seasonal, financial and economic factors; (3) quantitative analysis of the relative risk-return characteristics of investments and a comparison of yields between asset classes and other indicators; and (4) analysis of proprietary and secondary models. In evaluating a particular company, we put more emphasis on credit considerations (such as (1) loan-to-value ratio (which is the amount of our loan divided by the enterprise value of the company in which we are investing), (2) the ability of the company to maintain a liquidity cushion through

economic cycles and in downside scenarios, (3) the ability of the company to service its fixed charge obligations under a variety of scenarios and (4) its anticipated strategic value in a downturn) than on profit potential and loan pricing. Based upon a combination of bottom-up analysis of the individual investment and GC Advisors’ expectations of future market conditions, GC Advisors seeks to assess the relative risk and reward for each investment. GC Advisors seeks to mitigate the risks of a single company or single industry through portfolio diversification. GC Advisors also considers environmental, social and governance considerations in the investment decision-making process, in accordance with its ESG policy, including analysis of the likelihood of material ESG-related risk based on the industry and industry subsector of the potential portfolio company, with further diligence and analysis based on this categorization as well as other factors identified during diligence. ESG related risks can include, among others, issues related to environmental impact and climate change, anti-discrimination and anti-harassment, data privacy and security, social and labor conditions and ethics and compliance. Although GC Advisors typically avoids investing in portfolio companies in industries that tend to raise ESG related risks, GC Advisors would not necessarily pass on such investment opportunities solely for ESG reasons. Golub Capital’s due diligence process for middle-market credits will typically entail:

•a thorough review of historical and pro forma financial information;

•on-site visits;

•interviews with management and employees;

•a review of loan documents and material contracts;

•third-party “quality of earnings” accounting due diligence;

•when appropriate, background checks on key managers and research relating to the company’s business, industry, markets, customers, suppliers, products and services and competitors; and

•the commission of third-party market studies when appropriate.

The following chart illustrates the stages of Golub Capital’s evaluation and underwriting process:

ILLUSTRATIVE DEAL EVALUATION PROCESS

Execution. In executing transactions for us, GC Advisors utilizes the due diligence process developed by Golub Capital. Through a consistent approach to underwriting and careful attention to the details of execution, Golub Capital seeks to maintain discipline with respect to credit, pricing, and structure to ensure the ultimate success of the financing. Upon completion of due diligence, the investment team working on an investment delivers a final memorandum to GC Advisors’ investment committee. Once an investment has been approved by the investment committee, it moves through a series of steps generally, including initial documentation using standard document templates, final documentation, including resolution of business points and the execution of original documents held in escrow. Upon completion of final documentation, a loan is funded upon the execution of an investment committee memorandum by members of GC Advisors’ investment committee.

Monitoring. We view active portfolio monitoring as a vital part of our investment process. We consider board observation rights, where appropriate, regular dialogue with company management and sponsors and detailed,

internally generated monitoring reports to be critical to our performance. Golub Capital has developed a monitoring template that is designed to reasonably ensure compliance with these standards. This template is used by GC Advisors as a tool to assess investment performance relative to our plan. In addition, our portfolio companies often rely on GC Advisors to provide them with financial and capital markets expertise.

As part of the monitoring process, GC Advisors regularly assesses the risk profile of each of our investments and rates each of them based on an internal system developed by Golub Capital and its affiliates. This system is not generally accepted in our industry or used by our competitors. It is based on the following categories, which we refer to as GC Advisors’ internal performance ratings:

Internal Performance Ratings

Rating Definition

5 Involves the least amount of risk in our portfolio. The borrower is performing above expectations, and the trends and risk factors are generally favorable.

4 Involves an acceptable level of risk that is similar to the risk at the time of origination. The borrower is generally performing as expected, and the risk factors are neutral to favorable.

3 Involves a borrower performing below expectations and indicates that the loan’s risk has increased somewhat since origination. The borrower could be out of compliance with debt covenants; however, loan payments are generally not past due.

2 Involves a borrower performing materially below expectations and indicates that the loan’s risk has increased materially since origination. In addition to the borrower being generally out of compliance with debt covenants, loan payments could be past due (but generally not more than 180 days past due).

1 Involves a borrower performing substantially below expectations and indicates that the loan’s risk has substantially increased since origination. Most or all of the debt covenants are out of compliance and payments are substantially delinquent. Loans rated 1 are not anticipated to be repaid in full and we will reduce the fair market value of the loan to the amount we anticipate will be recovered.

Our internal performance ratings do not constitute any rating of investments by a nationally recognized statistical rating organization or represent or reflect any third-party assessment of any of our investments.

For any investment rated 1, 2 or 3, GC Advisors increases its monitoring intensity and prepares regular updates for the investment committee, summarizing current operating results and material impending events and suggesting recommended actions.

GC Advisors monitors and, when appropriate, changes the internal performance ratings assigned to each investment in our portfolio. In connection with our valuation process, GC Advisors and our board of directors review these internal performance ratings on a quarterly basis.

The following table shows the distribution of our investments on the 1 to 5 internal performance rating scale at fair value as of September 30, 2025 and 2024:

September 30, 2025 September 30, 2024

Internal

Performance

Rating
Investments

at Fair Value

(In thousands)
Percentage of

Total

Investments
Investments

at Fair Value

(In thousands)
Percentage of

Total

Investments

5 $ 157,871 1.8 $ 158,656 1.9

4 7,683,585 87.6 7,013,631 85.2

3 843,352 9.6 955,079 11.6

2 84,581 1.0 108,045 1.3

1 — — — —

Total $ 8,769,389 100.0 $ 8,235,411 100.0

Investment Committee

The purpose of GC Advisors’ investment committee, which is comprised of officers of GC Advisors, is to evaluate and approve all of our investments, subject to the oversight of our board of directors. The investment committee process is intended to bring the diverse experience and perspectives of the committee’s members to the analysis and consideration of each investment. The investment committee currently consists of Lawrence E. Golub, David B. Golub, Andrew H. Steuerman, Gregory W. Cashman, Spyro G. Alexopoulos, Marc C. Robinson, Robert G.

Tuchscherer and Jason J. Van Dussen. The investment committee serves to provide investment consistency and adherence to our core investment philosophy and policies. The investment committee also determines appropriate investment sizing and suggests ongoing monitoring requirements.

In addition to reviewing investments, investment committee meetings serve as a forum to discuss credit views and outlooks. Potential transactions and deal flow are reviewed on a regular basis. Members of the investment team are encouraged to share information and credit views with the investment committee early in their analysis. We believe this process improves the quality of the analysis and assists the deal team members to work more efficiently.

Each transaction is presented to the investment committee in a formal written report. Each investment opportunity generally receives the unanimous approval of the investment committee. Each member of the investment committee performs a similar role for other investment funds, accounts or other investment vehicles, collectively referred to as accounts, sponsored or managed by Golub Capital and its affiliates.

Investment Structure

Once GC Advisors determines that a prospective portfolio company is suitable for investment, GC Advisors typically works with the private equity sponsor, if applicable, the management of that company and its other capital providers to structure our investment. GC Advisors negotiates with these parties to agree on how our investment should be structured relative to other capital in the portfolio company’s capital structure.

GC Advisors structures our investments, which typically have maturities of three to seven years, as follows:

Senior Secured Loans. GC Advisors structures investments in senior secured loans, where we obtain security interests in the assets of the portfolio company that serve as collateral in support of the repayment of such loans. This collateral often takes the form of first-priority liens on the assets of the portfolio company. Our senior secured loans often provide for moderate loan amortization in the early years of the loan, with the majority of the amortization deferred until loan maturity. Our senior secured loans could include a payment in kind, or PIK, feature.

One Stop Loans. GC Advisors structures our one stop loans as senior secured loans. A one stop loan is a single loan that blends the characteristics of traditional senior debt and traditional junior debt. The structure generally combines the stronger lender protections associated with first lien senior secured debt with the superior economics of junior capital. We obtain security interests in the assets of the portfolio company that serve as collateral in support of the repayment of these loans. This collateral often takes the form of first-priority liens on the assets of the portfolio company. In some cases, one stop loans are provided to borrowers experiencing high revenue growth supported by a high level of discretionary expenditures. As part of the underwriting of such loans and consistent with industry practice, we adjust our characterization of the earnings of such borrowers for a reduction or elimination of such discretionary expenses if appropriate. One stop loans typically provide for moderate loan amortization in the initial years of the facility, with the majority of the amortization deferred until loan maturity. Our one stop loans could include a PIK feature. One stop loans generally allow the borrower to make a large lump sum payment of principal at the end of the loan term and there is a risk of loss if the borrower is unable to pay the lump sum or refinance the amount owed at maturity. In many cases, we are the sole lender or we, together with our affiliates, are the sole lenders of a one stop loan, which can afford us additional influence over the borrower in terms of monitoring and, if necessary, remediating any underperformance.

One stop loans include loans to technology companies undergoing strong growth due to new services, increased adoption and/or entry into new markets. We refer to loans to these companies as recurring revenue loans. Other targeted characteristics of recurring revenue businesses include strong customer revenue retention rates, a diversified customer base and backing from growth equity or venture capital firms. In some cases, the borrower’s high revenue growth is supported by a high level of discretionary spending. As part of the underwriting of such loans and consistent with industry practice, we adjust our characterization of the earnings of such borrowers for a reduction or elimination of such discretionary expenses, if appropriate.

Second Lien Loans. GC Advisors structures these investments as subordinated, secured loans for which our claims on the related collateral are subordinated. We obtain security interests in the assets of the portfolio company that serve as collateral in support of the repayment of such loans. This collateral typically takes the form of second priority liens on the assets of a portfolio company. Second lien loans typically provide for minimal loan amortization in the initial years of the facility, with the majority of the amortization deferred until loan maturity.

Subordinated Loans. GC Advisors structures these investments as unsecured, subordinated loans that provide for relatively high, fixed interest rates and provide us with significant current interest income. These loans typically have interest-only payments (often representing a combination of cash pay and PIK interest) in the early years, with all or the majority of amortization of principal deferred until loan maturity. Subordinated loans generally allow the borrower to make a large lump sum payment of principal at the end of the loan term, and there is a risk of loss if the borrower is unable to pay the lump sum or refinance the amount owed at maturity.

Second lien loans and subordinated loans are generally more volatile than first lien, senior secured loans and involve a greater risk of loss of principal. In addition, the PIK feature of many subordinated loans, which effectively operates as negative amortization of loan principal, increases credit risk exposure over the life of the loan. Subordinated loans are more likely to include a PIK feature.

Equity Investments. GC Advisors structures these investments as direct or indirect minority equity co-investments in a portfolio company, usually on terms similar to the controlling private equity sponsor and in connection with our loan to such portfolio company. As a result, if a portfolio company appreciates in value, we can achieve additional investment return from these equity co-investments. GC Advisors can structure these equity co-investments to include provisions protecting our rights as a minority-interest holder, which could include a “put,” or right to sell such securities back to the issuer, upon the occurrence of specified events or demand and “piggyback” registration rights. However, because these equity co-investments will typically be in private companies, there is no guarantee that we, as a minority-interest holder, will control the timing or value of our realization of any gains on such investments.

Our equity co-investments will typically include customary “tag-along” and/or “drag-along” rights that will permit or require us to participate in a sale of such equity co-investments at such time as the majority owners, not GC Advisors, determine.

GC Advisors tailors the terms of each investment to the facts and circumstances of the transaction and the prospective portfolio company, negotiating a structure that protects our rights and manages our risk while creating incentives for the portfolio company to achieve its business plan and improve its operating results. GC Advisors seeks to limit the downside potential of our investments by:

•selecting investments that we believe have a very low probability of loss;

•requiring a total return on our investments that we believe will compensate us appropriately for credit risk; and

•negotiating covenants in connection with our investments that afford our portfolio companies as much flexibility in managing their businesses as possible, consistent with the preservation of our capital. Such restrictions could include affirmative and negative covenants, default penalties, lien protection, change of control provisions and board rights.

We expect to hold most of our investments to maturity or repayment, but we could sell some of our investments earlier if a liquidity event occurs, such as a sale, recapitalization or worsening of the credit quality of the portfolio company.

Investments

We seek to create a portfolio that includes primarily one stop and other senior secured loans by investing approximately $10.0 million to $85.0 million of capital, on average, in the securities of middle-market companies. We also selectively invest more than $85.0 million in some of our portfolio companies and generally expect that the size of our individual investments will vary proportionately with the size of our capital base. Set forth below is a list of our ten largest portfolio company investments as of September 30, 2025, as well as the top ten industries in which we were invested as of September 30, 2025, calculated as a percentage of our total investments at fair value as of such date.

Portfolio Company Investments at

Fair Value

(In thousands) Percentage of

Total

Investments

GS Acquisitionco, Inc. $ 181,091 2.1 %

Bayshore Intermediate #2, L.P. 131,762 1.5

TWAS Holdings, LLC 111,851 1.3

Chestnut Optical Midco, Inc. 101,952 1.2

Liminex, Inc. 95,134 1.1

PHM NL SP Bidco B.V. 89,261 1.0

Blue River Pet Care, LLC 89,154 1.0

Riskonnect Parent, LLC 87,434 1.0

Revalize, Inc. 87,060 1.0

Amalthea Parent, Inc. 85,133 1.0

$ 1,059,832 12.2 %

Industry Investments at

Fair Value

(In thousands) Percentage of

Total Investments

Software $ 2,387,723 27.2 %

Healthcare Providers & Services 645,551 7.4

Diversified Consumer Services 462,485 5.3

Specialty Retail 436,744 5.0

Insurance 426,028 4.9

Automobiles 417,389 4.8

Healthcare Technology 406,376 4.6

Healthcare Equipment & Supplies 332,338 3.8

Pharmaceuticals 322,002 3.7

IT Services 292,679 3.3

$ 6,129,315 70.0 %

Managerial Assistance

As a business development company, we offer, and must provide upon request, managerial assistance to our portfolio companies. This assistance could involve monitoring the operations of our portfolio companies, participating in board and management meetings, consulting with and advising officers of portfolio companies and providing other organizational and financial guidance. The Administrator or an affiliate of the Administrator provides such managerial assistance on our behalf to portfolio companies that request this assistance. We could receive fees for these services and reimburse the Administrator or an affiliate of the Administrator, as applicable, for its allocated costs in providing such assistance, subject to the review and approval by our board of directors, including our independent directors.

Competition

Our primary competitors in providing financing to middle-market companies include public and private funds, other business development companies, commercial and investment banks, commercial financing companies and, to the extent they provide an alternative form of financing, private equity and hedge funds. Many of our competitors are substantially larger and have considerably greater financial, technical and marketing resources than we do. For example, we believe some competitors have access to funding sources that are not available to us. In addition, some of our competitors have higher risk tolerances or different risk assessments, which could allow them to consider a wider variety of investments and establish more relationships than us. Furthermore, many of our competitors are not subject to the regulatory restrictions that the 1940 Act imposes on us as a business development company or to the source-of-income, asset diversification and distribution requirements we must satisfy to maintain our qualification as a RIC.

We use the expertise of the investment professionals of Golub Capital and its affiliates to which we have access to assess investment risks and determine appropriate pricing for our investments in portfolio companies. In addition, the relationships of the senior members of Golub Capital and its affiliates enable us to learn about, and compete effectively for, financing opportunities with attractive middle-market companies in the industries in which we invest. See “Risk Factors — Risks Relating to our Business and Structure — We operate in a highly competitive market for investment opportunities, which could reduce returns and result in losses.”

Administration

We do not have any direct employees, and our day-to-day investment operations are managed by GC Advisors. Our business and affairs are managed under the direction of our board of directors. We have a chief executive officer, chief financial officer, chief compliance officer, managing director and director of corporate strategy, and to the extent necessary, our board of directors can elect to appoint additional officers going forward. Our officers are officers and/or employees of Golub Capital LLC, an affiliate of GC Advisors, and our allocable portion of the cost of our chief financial officer and chief compliance officer and their respective staffs is paid by us pursuant to the administration agreement, or the Administration Agreement, with the Administrator. See “Business - Management Agreements - Administration Agreement.”

SUMMARY RISK FACTORS

The risk factors described below are a summary of the principal risk factors associated with an investment in us. These are not the only risks we face. You should carefully consider these risk factors, together with the risk factors set forth in