Golub Capital BDC : Quarter Ended 12.31.2023 Investor Presentation

Disclaimer

Some of the statements in this presentation constitute forward-looking statements, which relate to future events or our future performance or financial condition. The forward-looking statements contained in this presentation involve risks and uncertainties, including statements as to: our future operating results; our business prospects and the prospects of our portfolio companies, including our and their ability to achieve our respective objectives due to disruptions, including those caused by global health pandemics, such as the COVID-19 pandemic, or other large scale events; the effect of investments that we expect to make and the competition for those investments; our contractual arrangements and relationships with third parties; actual and potential conflicts of interest with GC Advisors LLC ("GC Advisors"), our investment adviser, and other affiliates of Golub Capital LLC (collectively, "Golub Capital"); the dependence of our future success on the general economy and its effect on the industries in which we invest; the ability of our portfolio companies to achieve their objectives; the use of borrowed money to finance a portion of our investments; the adequacy of our financing sources and working capital; the timing of cash flows, if any, from the operations of our portfolio companies; general economic and political trends and other external factors, including the COVID-19 pandemic; changes in political, economic or industry conditions, the interest rate environment or conditions affecting the financial and capital markets that could result in changes to the value of our assets; elevating levels of inflation, and its impact on us, on our portfolio companies and on the industries in which we invest; the ability of GC Advisors to locate suitable investments for us and to monitor and administer our investments; the ability of GC Advisors or its affiliates to attract and retain highly talented professionals; the ability of GC Advisors to continue to effectively manage our business due to disruptions, including those caused by global health pandemics, such as the COVID-19 pandemic or other large scale events; turmoil in Ukraine and Russia, including sanctions related to such turmoil, and the potential for volatility in energy prices and other supply chain issues and any impact on the industries in which we invest; our ability to qualify and maintain our qualification as a regulated investment company, or RIC, and as a business development company; the impact of information technology systems and systems failures including data security breaches, data privacy compliance, network disruptions, and cybersecurity

attacks; general price and volume fluctuations in the stock markets; the impact on our business of the Dodd-Frank Wall Street Reform and Consumer Protection Act and the rules and regulations issued thereunder and any actions toward repeal thereof; and the effect of changes to tax legislation and our tax position.

Such forward-looking statements may include statements preceded by, followed by or that otherwise include the words "may," "might," "will," "intend," "should," "could," "can," "would," "expect," "believe," "estimate," "anticipate," "predict," "potential," "plan" or similar words. The forward-looking statements contained in this presentation involve risks and uncertainties. Our actual results could differ materially from those implied or expressed in the forward-looking statements for any reason, including the factors set forth as "Risk Factors" in our annual reports on our Form 10-K, registration statements on Form N-2, and quarterly reports on Form 10-Q.

We have based the forward-looking statements included in this presentation on information available to us on the date of this presentation. Actual results could differ materially from those anticipated in our forward-looking statements and future results could differ materially from historical performance. You are advised to consult any additional disclosures that we may make directly to you or through reports that we have filed or in the future file with the Securities and Exchange Commission ("SEC"), including annual reports on Form 10-K, registration statements on Form N-2, quarterly reports on Form 10-Q and current reports on Form 8-K.

This presentation contains statistics and other data that have been obtained from or compiled from information made available by third-party service providers. We have not independently verified such statistics or data.

In evaluating prior performance information in this presentation, you should remember that past performance is not a guarantee, prediction, or projection of future results, and there can be no assurance that we will achieve similar results in the future.

GBDC Value Proposition:

We Believe GBDC is Well Positioned Against:

• Invests in first lien first outsenior secured floating rateloans
• Borrowers in resilient industries backed by partnership-oriented, top- quality private equity firms

• Golub Capital has a history of strong underwriting and low credit losses
• We believe Golub Capital has meaningful competitive advantages from its scale, relationships and incumbencies

• Durable leverage structure with 62% unsecured funding ratio
• Leading fee structure with among the highest industry hurdle rates
• Strong alignment with manager and lifetime cumulative incentive fee lookback

• Enhanced dividend yield profile on quarterly distribution increase and variable supplemental distribution framework
• Designed for resiliency across a wide range of potential economic scenarios

Predominantly First Lien, First Out Senior Secured Loan Portfolio Mitigates Credit Risk

Preponderance of Portfolio is Floating Rate, Mitigating Interest Rate Risk

Portfolio Composition by Seniority

1%

5% 8%

94%

First Lien

86%

First Lien Traditional

Senior

First Lien

One Stop

Junior Debt1

Equity

Portfolio Composition by Interest Rate Type on Loans2

Internal Performance Ratings3 Are Back Near Pre-Covid Levels, Highlighting Our Focus on Resilient Companies and Industries

Highly Granular and Diversified Portfolio Limits the Potential Impact of Idiosyncratic Risks

Internal Performance Rating Migration

% of Portfolio at Fair Value

September 30, March 31, 2020 December 31, 2023 2019

Internal Performance Ratings 4-5

(Performing At or Above Expectations)

Internal Performance Rating 3

(Performing Below Expectations)

Internal Performance Ratings 1-2

(Performing Materially Below Expectations)

0.3% Average Investment Size

40industries below 3%

Software 27%

Portfolio Composition by Seniority1

GBDC's portfolio is more conservatively positioned than the

BDC peer average

94% First Lien

75% First Lien

Diversification by Obligor

GBDC's portfolio is almost twice as diversified by obligor as the BDC

peer average

357 Portfolio Companies

(0.28% Average Investment Size1)

185 Portfolio Companies2

(0.54% Average Investment Size)

Realized & Unrealized Net Gain/(Loss) Rate Since Inception

Annualized, % of portfolio at cost1

GBDC has earned an annualized net investment gainrate

since inception

0.22%

(0.11%)

(0.90%)

(1.59%)

Volatility of Quarterly Loss Rates Since Inception

Standard deviation, % of portfolio at cost

GBDC has the lowest volatility of quarterly loss rates

as compared to the BDCs in the peer group

2.09%

1.72%

1.32%

0.95%

CQ2 2020 - CQ1 2021 Realized Net Gains (Losses)

Annualized, % of portfolio at cost1

GBDC delivered leading sector performancethrough the

COVID-impacted period

(0.22%) (0.16%)

(0.58%)

CQ2 2020 - CQ1 2021 Volatility of Quarterly Loss Rates

Standard Deviation, % of portfolio at cost

GBDC has the lowest volatility of quarterly realized loss rates through

the COVID-impacted period

0.78%

0.55%

0.14%

0.05%