Indicate by check mark if each registrant is a well-known seasoned issuer, as defined in Rule 405 of the Securities Act.

Indicate by check mark if each registrant is not required to file reports pursuant to Section 13 or Section 15(d) of the Exchange Act.

Indicate by check mark whether each registrant (1) has filed all reports required to be filed by Section 13 or 15(d) of the Securities Exchange Act of 1934 during the preceding 12 months (or for such shorter period that the registrant was required to file such reports) and (2) has been subject to such filing requirements for the past 90 days.

DPL Inc. and The Dayton Power and Light Company have filed all applicable reports under Section 13 or 15(d) of the Securities Exchange Act of 1934 during the preceding 12 months.

Indicate by check mark whether each registrant has submitted electronically every Interactive Data File required to be submitted pursuant to Rule 405 of Regulation S-T during the preceding 12 months (or for such shorter period that the registrant was required to submit such files).

Indicate by check mark whether the registrant is a large accelerated filer, an accelerated filer, a non-accelerated filer, a smaller reporting company or an emerging growth company. See the definitions of “large accelerated filer,” “accelerated filer”, “smaller reporting company” and "emerging growth company" in Rule 12b-2 of the Exchange Act.

If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 13(a) of the Exchange Act.

Indicate by check mark whether each registrant is a shell company (as defined in Rule 12b-2 of the Exchange Act).

All of the outstanding common stock of DPL Inc. is indirectly owned by The AES Corporation. All of the common stock of The Dayton Power and Light Company is owned by DPL Inc.

At December 31, 2022,2023, each registrant had the following shares of common stock outstanding:

This combined Form 10-K is separately filed by DPL Inc. and The Dayton Power and Light Company. Information contained herein relating to any individual registrant is filed by such registrant on its own behalf. Each registrant makes no representation as to information relating to a registrant other than itself.

THE REGISTRANTS MEET THE CONDITIONS SET FORTH IN GENERAL INSTRUCTION I(1)(a) AND (b) OF FORM 10-K AND ARE THEREFORE FILING THIS FORM WITH THE REDUCED DISCLOSURE FORMAT.

The following select terms, abbreviations or acronyms are used in this Form 10-K:

This report includes the combined filing of DPL and of DP&L, which does business as and is also referred to herein as AES Ohio. DPL is a wholly-owned subsidiary of AES, a global powerenergy company. Throughout this report, the terms "the Company", “we”, “us”, “our” and “ours” are used to refer to both DPL and DP&L, respectively and altogether, unless the context indicates otherwise. Discussions or areas of this report that apply only to DPL or DP&L will clearly be noted in the section.

Certain statements contained in this report are “forward-looking statements” within the meaning of the Private Securities Litigation Reform Act of 1995. Matters discussed in this report that relate to events or developments that are expected to occur in the future, including management’s expectations, strategic objectives, business prospects, anticipated economic performance and financial condition and other similar matters constitute forward-looking statements. Forward-looking statements are based on management’s beliefs, assumptions and expectations of future economic performance, considering the information currently available to management. These statements are not statements of historical fact and are typically identified by terms and phrases such as “anticipate”, “believe”, “intend”, “estimate”, “expect”, “continue”, “should”, “could”, “may”, “plan”, “project”, “predict”, “will” and similar expressions. Such forward-looking statements are subject to risks and uncertainties and investors are cautioned that outcomes and results may vary materially from those projected due to various factors beyond our control, including but not limited to:

Forward-looking statements speak only as of the date of the document in which they are made. We disclaim any obligation or undertaking to provide any updates or revisions to any forward-looking statement to reflect any change in our expectations or any change in events, conditions or circumstances on which the forward-looking statement is based. If we do update one or more forward-looking statements, no inference should be made that we will make additional updates with respect to those or other forward-looking statements.

DPL is a regional energy company incorporated in 1985 under the laws of Ohio. All of DPL’s stock is owned by an AES subsidiary.

MVIC is our captive insurance company that provides insurance services to AES Ohio and our other subsidiaries, and Miami Valley Lighting provides street and outdoor lighting services to customers in the Dayton region. DPL also has a wholly-owned business trust, DPL Capital Trust II, formed for the purpose of issuing trust capital securities to investors.

AES Ohio’s electric transmission and distribution businesses are subject to rate regulation by federal and state regulators. Accordingly, AES Ohio applies the accounting standards for regulated operations to its electric transmission and distribution businesses and records regulatory assets when incurred costs are expected to be recovered in future customer rates and regulatory liabilities when current cost recoveries in customer rates relate to expected future costs or overcollections of riders. AES Ohio also has a 4.9% interest in OVEC, an electric generating company. OVEC has two electric generating stations located in Cheshire, Ohio and Madison, Indiana with a combined generation capacity of 2,109 MW. AES Ohio’s share of this generation capacity is 103 MW. AES Ohio does not have any subsidiaries.

DPL's employees are essential to delivering and maintaining reliable service to our customers. DPL and its subsidiaries employed 657710 people (547(628 full-time) at December 31, 2022,2023, all of whom were employed by AES Ohio. Approximately 58%60% of all DPL employees are under a collective bargaining agreement that expires on October 31, 2023.2026.

As part of AES, safety is one of our core values. Conducting safe operations at our facilities, so that each person can return home safely, is the cornerstone of our daily activities and decisions. Safety efforts are led globally by the AES Chief Operating Officer and supported by safety committees that operate at the local site level. Hazards in the workplace are actively identified and management tracks incidents so remedial actions can be taken to improve workplace safety.

We work with the AES Safety Management System (“SMS”), a global safety standard that applies to all AES employees and employees of AES subsidiaries, as well as contractors working in AES facilities and construction projects. The SMS requires continuous safety performance monitoring, risk assessment and performance of periodic integrated environmental, health and safety audits. The SMS provides a consistent framework for all AES operational businesses and construction projects to set expectations for risk identification and reduction, measure performance and drive continuous improvements. The SMS standard is consistent with the OHSA 18001/ISO 45001 standard. Our safety performance is also measured by both leading and lagging metrics. Our leading safety metrics track safety observations, safety meeting engagement and the reporting of non-injury significant injury potential incidents.lost time incident rates for our employees and contractors based on OSHA standards. Our lagging safety metrics track lost workday cases, severity rate, and recordable incidents. We are committed to excellence in safety and have implemented various programs to increase safety awareness and improve work practices.

We believe our success depends on our ability to attract, develop and retain key personnel. The skills, experience and industry knowledge of key employees significantly benefit our operations and performance. We have a comprehensive approach to managing our talent and developing our leaders in order to ensure our people have the right skills for today and tomorrow whether that requires us to build new business models or leverage leading technologies.

We emphasize employee development and training. To empower employees, we provide a range of development programs and opportunities, skills, and resources they need to be successful by focusing on experience and exposure as well as formal programs including the AES ACE Academy for Talent Development and our Trainee Program.

We believe that our individual differences make us stronger. Our Global Diversity and Inclusion Program is led by the AES Diversity and Inclusion Officer. Governance and standards are guided by the AES Chief Human Resources Officer, with input from members of AES' Executive Leadership Team.

Our compensation philosophy emphasizes pay-for-performance. Our incentive plans are designed to reward strong performance, with greater compensation paid when performance exceeds expectations and less compensation paid when performance falls below expectations. We invest significant time and resources to ensure our compensation programs are competitive and reward the performance of our people. Every year, our people who are not part of a collective bargaining agreement are eligible for an annual merit-based salary increase. In addition, individuals are eligible for a salary increase if they receive a significant promotion. For non-collectively bargained employees at certain levels in the organization we offer annual incentives (bonus) and long-term compensation to reinforce the alignment between employees and AES.

The Service Company provides services including operations, accounting, legal, human resources, information technology and other corporate services on behalf of companies that are part of thecertain AES U.S. SBU,companies including, among other companies, DPL and AES Ohio. The Service Company allocates the costs for these services based on cost drivers designed to result in fair and equitable allocations. This includes ensuring that the regulated utilities served,

The power delivery business is seasonal, and weather patterns have a material effect on energy demand. In the region we serve, demand for electricity is generally greater in the summer months associated with cooling and in the winter months associated with heating compared to other times of the year. AES Ohio's sales typically reflect the seasonal weather patterns but can also be impacted by service territory economic activity the economic impact of the COVID-19 pandemic, and the number of retail customers we have, as well as customer-initiated energy efficiency programs. During 2019, the impacts of weather, energy efficiency programs and economic changes in customer demand were almost entirely eliminated by AES Ohio’s Decoupling Rider, which was in place from January 1, 2019 until December 18, 2019. AES Ohio has requested authority from the PUCO to create a regulatory asset for the ongoing revenues that would have been charged in the Decoupling Rider going back to December 18, 2019. A hearing on this request was held in May 2021 and is pending a decision by the PUCO. See Note 2 – REGULATORY MATTERS of Notes to DPL's Consolidated Financial Statements and Note 2 – REGULATORY MATTERS of Notes to AES Ohio's Financial Statements.efforts.

Storm activity can also have an adverse effect on our operating performance. Severe storms often damage transmission and distribution equipment, thereby causing power outages, which reduce revenuesrevenue and increase repair costs. Partially mitigating this impact is AES Ohio’s ability to timely recover certain O&M repair costs related to severe storms.

AES Ohio's distribution service to all retail customers as well as the provisions of its SSO service are regulated by the PUCO. In addition, certain costs are considered to be non-bypassable and are therefore assessed to all AES Ohio retail customers, under the regulatory authority of the PUCO, regardless of the customer’s retail electric supplier. AES Ohio's transmission rates are subject to regulation by the FERC under the Federal Power Act.

Ohio law establishes the process for determining SSO and non-bypassable rates charged by public utilities. Regulation of retail rates encompasses the timing of applications, the effective date of rate changes, the cost basis upon which the rates are set and other service-related matters. Ohio law also established the Office of the Ohio Consumers' Counsel, which has the authority to represent residential consumers in state and federal judicial and administrative rate proceedings.

Ohio legislation extends the jurisdiction of the PUCO to the records and accounts of certain public utility holding company systems, including DPL. The legislation extends the PUCO's supervisory powers to a holding company system's general condition and capitalization, among other matters, to the extent that such matters relate to the costs associated with the provision of public utility service. Based on existing PUCO and FERC authorization, regulatory assets and liabilities are recorded on the balance sheets of both DPL and AES Ohio. See

AES Ohio rates for transmission and distribution electric service currently remain the lowest among Ohio investor-owned utilities.

On September 26, 2022, AES Ohio filed its latest ESP 1 established(ESP 4) with the PUCO. ESP 4 is a comprehensive plan to enhance and upgrade its network and improve service reliability, provide greater safeguards for price stability and continue investments in local economic development. On April 10, 2023, AES Ohio's framework for providing retail service onOhio entered into a going-forward basis including rate structures, non-bypassable chargesStipulation and other specific rate recovery true-up rider mechanisms. For more information regarding AES Ohio's ESP, see Note 2 – REGULATORY MATTERS of Notes to DPL's Consolidated Financial StatementsRecommendation with the PUCO Staff and Note 2 – REGULATORY MATTERS of Notesseventeen parties (the “Settlement”) with respect to AES Ohio's Financial Statements.Ohio’s ESP 4 application, and, on August 9, 2023, the PUCO approved the Settlement without modification. With approval of this Settlement, the distribution rates that were approved by the PUCO on December 14, 2022, and are described in the paragraph below, became effective on September 1, 2023.

Ohio law and the PUCO rules contain targets relating to renewable energy standards. AES Ohio is currently in full compliance with renewable energy standards. AES Ohiostandards and recovers the costs of its compliance with Ohio renewable energy standards through its Standard Offer Rate Tariff, which is reviewed and audited by the PUCO.

The costs associated with providing high voltage transmission service and wholesale electric sales and ancillary services are subject to FERC jurisdiction. AES Ohio implemented a formula-based rate for its transmission service, effective May 3, 2020. For more information, see Note 2 – REGULATORY MATTERS of Notes to DPL's Consolidated Financial Statements and Note 2 – REGULATORY MATTERS of Notes to AES Ohio's Financial Statements.

As a member of PJM, AES Ohio also receives revenuesrevenue from the RTO related to AES Ohio’s transmission assets and incurs costs associated with its load obligations for retail customers. Ohio law includes a provision that would allow Ohio electric utilities to seek and obtain a reconcilable rider to recover RTO-related costs and credits. AES Ohio continues to recover non-market-based transmission and ancillary costs through its non-bypassable Transmission Cost Recovery Rider.

Since January 2001, AES Ohio’s electric customers have been permitted to choose their retail electric generation supplier. The SSO generation supply is provided by third parties through a competitive bid process. AES Ohio continues to have the exclusive right to provide delivery service in its state-certified territory and the obligation to procure and provide electricity to SSO customers that do not choose an alternative supplier. The PUCO maintains jurisdiction over AES Ohio’s delivery of electricity, SSO and other retail electric services.

As part of Ohio’s electric deregulation law, all of the state’s investor-owned utilities were required to join an RTO. AES Ohio is a member of the PJM RTO. The role of the RTO is to administer a competitive wholesale market for electricity and ensure reliability of the transmission grid. PJM ensures the reliability of the high-voltage electric power system serving more than 65 million people in all or parts of Delaware, Illinois, Indiana, Kentucky, Maryland, Michigan, New Jersey, North Carolina, Ohio, Pennsylvania, Tennessee, Virginia, West Virginia and the District of Columbia. PJM coordinates and directs the operation of the region’s transmission grid, administers the world’s largest competitive wholesale electricity market and plans regional transmission expansion improvements to maintain grid reliability and relieve congestion.

We are subject to various federal, state, regional and local environmental protection and health and safety laws and regulations governing, among other things, the generation, storage, handling, use, disposal and transportation of regulated materials, including ash; the use and discharge of water used in generation boilers and for cooling purposes; the emission and discharge of hazardous and other materials, including GHGs, into the environment; climate change; and the health and safety of our employees. These laws and regulations often require a lengthy and complex process of obtaining and renewing permits and other governmental authorizations from federal, state

Where no accrued liability has been recognized, it is reasonably possible that some matters could have unfavorable outcomes for us and could require us to pay damages or make expenditures in amounts that could be material but could not be estimated as of December 31, 2022.2023.

We have taken steps to limit our exposure to environmental claims that could be raised with respect to our previously-owned and operated coal-fired generation units, but we cannot predict whether any such claims will be raised and, if they are, the extent to which they may have a material adverse effect on our results of operations, financial condition and cash flows.

From time to time, we are subject to enforcement actions for claims of noncompliance with environmental laws and regulations. DPL and AES Ohio cannot assure that they will be successful in defending against any claim of noncompliance. However, we do not believe any currently open environmental investigations will result in fines material to our results of operations, financial condition and cash flows.

Under certain environmental laws, we could be held responsible for costs relating to contamination at our past or present facilities and at third-party waste disposal sites. We could also be held liable for human exposure to hazardous substances or for other environmental damage. Our costs of complying with current and future environmental and health and safety laws, and our liabilities arising from past or future releases of, or exposure to, hazardous substances may adversely affect our business, results of operations, financial condition and cash flows. A discussion of the legislative and regulatory initiatives most likely to affect us follows.

As a result of DPL’s sale of its ownership interest in the Miami Fort and Zimmer Stations in 2017, retirement and subsequent sale of its Stuart and Killen Stations in 2019, and the retirement and sale of our interest in Conesville in 2020, thereby completing the exit of our generation business, the following environmental matters, regulations and requirements are now not expected to have a material impact on DPL:

As a result of DPL’s retirement and subsequent sale of its Stuart and Killen Stations, the sale of its ownership interest in the Miami Fort and Zimmer Stations, retirement and subsequent sale of its Stuart and Killen Stations, and the 2020 retirement of Conesville, followed by theand sale of our interest in Conesville, and our exitingthereby completing the exit of our generation business, the following environmental matters, regulations and requirements are now not expected to have a material impact on DPL with respect to these generating stations (although certain other requirements related to water quality, waste disposal and ash ponds are discussed further below):

In December 2003, AES Ohio and other parties received notices that the EPA considered AES Ohio and other parties PRPs for the Tremont City Landfill site, located near Dayton, Ohio. On October 16, 2019, AES Ohio received another notice from the EPA claiming that AES Ohio is a PRP for the portion of the site known as the barrel fill. While a review by AES Ohio of its records indicates that it did not contribute hazardous materials to the site, AES Ohio is currently unable to predict the outcome of this matter. If AES Ohio were required to contribute to the clean-up of the site, it could have an adverse effect on our business, financial condition or results of operations.

On October 19, 2015, an EPA rule regulating CCR under the Resource Conservation and Recovery Act as nonhazardous solid waste became effective ("CCR Rule"). The rule established nationally applicable minimum criteria for the disposal of CCR in new and currently operating landfills and surface impoundments, including location restrictions, design and operating criteria, groundwater monitoring, corrective action and closure requirements and post-closure care. The 2016 Water Infrastructure Improvements for the Nation Act ("WIIN Act"), includes provisions to implement the CCR Rule through a state permitting program, or if the state chooses not to participate, a possible federal permit program. The EPA has indicated that they will implement a phased approach to amending the CCR Rule, which is ongoing. On February 20, 2020, the EPA published a proposed rule to establish a federal CCR permit program that would operate in states without approved CCR permit programs. With the sale of our coal-fired generating stations, we expect that the impact of these regulations would be limited to our interest in OVEC.

On August 28, 2020, the EPA published the CCR Part A Rule that, among other amendments, required certain CCR units to cease waste receipt and initiate closure by April 11, 2021. The CCR Part A Rule also allowed for extensions of the April 11, 2021 deadline if EPA determines certain criteria are met. Facilities seeking such an extension were required to submit a demonstration to EPA by November 30, 2020. On January 11, 2022, EPA released its first in a series of proposed determinations regarding nine CCR Part A Rule demonstrations, including for OVEC’s Clifty Creek and four compliance-related letters notifying certain other facilities of their compliance obligations under the federal CCR regulations. The determinations and letters include interpretations regarding implementation of the CCR Rule. On April 8, 2022, petitions for review were filed challenging these EPA actions. The petitions are consolidated in Electric Energy, Inc. v. EPA. It is too early to determine the direct or indirect impact of these letters or any determinations that may be made.

The CCR Rule, current or proposed amendments to, or EPA interpretations of, the CCR Rule, the results of groundwater monitoring data or the outcome of CCR-related litigation could have a material adverse effect on our results of operations, financial condition and cash flows.

On April 23, 2020, the U.S. Supreme Court issued a decision in the Hawaii Wildlife Fund v. County of Maui case related to whether a Clean Water Act permit is required when pollutants originate from a point source but are conveyed to navigable waters through a nonpoint source such as groundwater. The U.S. Supreme Court held that discharges to groundwater require a permit if the addition of the pollutants through groundwater is the functional equivalent of a direct discharge from the point source into navigable waters. A number of legal cases relevant to the determination of "functional equivalent" are ongoing in various jurisdictions. On November 27, 2023, the EPA issued draft guidance regarding functional equivalent discharge. It is too early to determine whether the Supreme Court decision or the result of litigation related to "functional equivalent" may have a material adverse effect on our results of operations, financial condition and cash flows.

The concept of "Waters of the U.S." ("WOTUS") defines the geographic reach and authority of the U.S. Army Corps of Engineers ("and the agencies"EPA (the "Agencies") publishedto regulate streams, wetlands, and other water bodies under the CWA. There have been multiple Supreme Court decisions and dueling regulatory definitions over the past several years concerning the proper standard for how to properly determine whether a rule defining federal jurisdiction over waters ofwetland or stream that is not navigable is considered a WOTUS. On May 25, 2023, the U.S., known as Supreme Court rendered a decision (the "Decision") in the "Waterscase of the U.S." ("WOTUS") rule. This rule, which initially became effective in August 2015, could expand or otherwise change the number and types of waters or features subject to CWA permitting. However, after repealing the 2015 WOTUS rule on October 22, 2019, the agencies, on April 21, 2020, issued the final “Navigable Waters Protection” ("NWP") rule which again revisedSackett v. Environmental Protection Agency, addressing the definition of watersWOTUS with regards to the CWA. The Decision provides a clear standard that substantially restricts the Agencies' ability to regulate certain types of the U.S. wetlands and streams. Specifically, wetlands that do not have a continuous surface connection with traditional interstate navigable water are not federally jurisdictional.

Although we have exited our generation business, our continuing operations face certain risks related to existing and potential international, federal, state, regional and local GHG legislation and regulations, including risks related to increased capital expenditures or other compliance costs which could have a material adverse effect on our results of operations, financial condition and cash flows. Except as noted in the discussion below, at this time, we cannot estimate the costs of compliance with existing, proposed or potential international, federal, state or regional GHG emissions reductions legislation or initiatives due in part to the fact that many of these proposals are in earlier stages of development and any final laws or regulations, if adopted, could vary drastically from current proposals. Any international, federal, state or regional legislation adopted in the U.S. that would require the reduction of GHG emissions could have a material adverse effect on our results of operations, financial condition and cash flows.

On the international level, on December 12, 2015, 195 nations, including the U.S., finalized the text of an international climate change accord in Paris, France (the “Paris Agreement”), which agreement was signed and

officially entered into on April 22, 2016. The Paris Agreement calls for countries to set their own GHG emissions targets, make these emissions targets more stringent over time and be transparent about the GHG emissions reporting and the measures each country will use to achieve its GHG emissions targets. A long-term goal of the

Paris Agreement is to limit global temperature increase to well below two degrees Celsius from temperatures in the

pre-industrial era. The U.S. withdrawal from the Paris Agreement became effective on November 4, 2020. However,

on January 20, 2021, President Biden signed and submitted an instrument for the U.S. to rejoin the Paris Agreement, which became effective on February 19, 2021. In November 2022,2023, the international community

gathered in Egypt atfor the 27th28th Conference to the Parties on the UN Framework Convention on Climate Change (“COP27”COP28”), during which multiple announcements were made, including the establishment of a loss and damage fund. The Parties agreed to support vulnerablenon-binding language calling on countries dealing with the effects of climate change and certain pledgesto transition away from fossil fuels in the area of climate finance.energy systems to achieve net zero emissions by 2050.

Customer growth is affected by a number of factors outside our control, such as population changes, job and income growth, housing starts, new business formation and the overall level of economic activity. A significant lack of growth, or a decline, in the number of customers in our service territory could have a material adverse effect on our results of operations, financial condition and cash flows and may cause us to fail to fully realize anticipated benefits from investments and expenditures.

Weather conditions significantly affect the demand for electric power and, accordingly, our business is affected by variations in general weather conditions and unusually severe weather. As a result of these factors, our operating revenuesrevenue and associated operating expenses are not generated evenly by month during the year. We forecast electric sales based on normal weather, which represents a long-term historical average. In addition, severe or unusual weather, such as floods, tornadoes and ice or snowstorms, may cause outages and property damage that may require us to incur additional costs that may not be insured or recoverable from customers. While AES Ohio is permitted to seek recovery of storm damage costs, if AES Ohio is unable to fully recover such costs in a timely manner, it could have a material adverse effect on our results of operations, financial condition and cash flows.

On October 1, 2004, in compliance with Ohio law, AES Ohio turned over control of its transmission functions and fully integrated into PJM, a regional transmission organization.

The rules governing the various regional power markets may also change from time to time which could affect our costs and revenuesrevenue and have a material adverse effect on our results of operations, financial condition and cash flows. We may be required to expand our transmission system according to decisions made by PJM rather than our internal planning process. Various proposals and proceedings before the FERC may cause transmission rates to change from time to time. In addition, PJM developed and continues to refine rules associated with the allocation

Non-market-based RTO-related charges are being recovered from all retail customers through the Transmission Rider. If in the future, however, we are unable to recover all of these costs in a timely manner this could have a material adverse effect on our results of operations, financial condition and cash flows.

As members of PJM, AES Ohio is also subject to certain additional risks including those associated with the allocation of losses caused by unreimbursed defaults of other participants in PJM markets among PJM members and those associated with complaint cases filed against PJM that may seek refunds of revenuesrevenue previously earned by PJM members including AES Ohio. These amounts could be significant and have a material adverse effect on our results of operations, financial condition and cash flows.

Annually, PJM performs a review of the capital additions required to provide reliable electric transmission services throughout its territory. PJM traditionally allocated the costs of constructing these facilities to those entities that benefited directly from the additions. Over the last several years, however, some of the costs of constructing large, new transmission facilities have been “socialized” across PJM without a direct relationship between the costs assigned to and benefits received by particular PJM members. To date, the additional costs charged to AES Ohio

for large, new transmission approved projects have not been material. Over time, as more new transmission projects are constructed and if the allocation method is not changed, the annual costs could become material. AES Ohio is recovering the Ohio retail jurisdictional share of these allocated costs from its retail customers through the Transmission Rider. To the extent that any costs in the future are material and we are unable to recover them from our customers, such costs could have a material adverse effect on our results of operations, financial condition and cash flows.

The ongoing reliable performance of our transmission and distribution system is subject to risks due to, among other things, weather damage, intentional or unintentional damage, equipment or process failure, catastrophic events, such as fires and/or explosions, facility outages, labor disputes, accidents or injuries, operator error or inoperability of key infrastructure internal or external to us and events occurring on third party systems that interconnect to and affect our system. The failure of our transmission and distribution system to fully operate and deliver the energy demanded by customers could have a material adverse effect on our results of operations, financial condition and cash flows, and if such failures occur frequently and/or for extended periods of time, could result in adverse regulatory action. In addition, the advent and quick adoption of new products and services that require increased levels of electrical energy cannot be predicted and could result in insufficient transmission and distribution system capacity. Also, as a result of the above risks and other potential risks and hazards associated with transmission and distribution operations, we may from time to time become exposed to significant liabilities for which we may not have adequate insurance coverage. We maintain an amount of insurance protection that we believe is adequate, but there can be no assurance that our insurance will be sufficient or effective under all circumstances and against all hazards or liabilities to which we may be subject. Further, any increased costs or adverse changes in the insurance markets may cause delays or inability in maintaining insurance coverage on terms similar to those presently available to us or at all. A successful claim for which we are not fully insured could have a material adverse effect on our results of operations, financial condition and cash flows.

Our business, results of operations, financial condition and cash flows have been and will continue to be affected by general economic conditions. Slowing economic growth, credit market conditions, fluctuating consumer and business confidence, fluctuating commodity prices and other challenges currently affecting the general economy, have caused and may continue to cause some of our customers to experience deterioration of their businesses, cash flow shortages and difficulty obtaining financing. As a result, existing customers may reduce their electricity consumption and may not be able to fulfill their payment obligations to us in a normal, timely fashion. In addition,

We enter into transactions with and rely on many counterparties in connection with our business, including for purchased power, for our capital improvements and additions and to provide professional services, such as actuarial calculations, payroll processing and various consulting services. If any of these counterparties fails to perform its obligations to us or becomes unavailable, our business plans may be materially disrupted, we may be forced to discontinue certain operations if a cost-effective alternative is not readily available or we may be forced to enter into alternative arrangements at then-current market prices that may exceed our contractual prices and cause delays. Although our agreements are designed to mitigate the consequences of a potential default by the counterparty, our actual exposure may be greater than relief provided by these mitigation provisions. Any of the foregoing could result in regulatory actions, cost overruns, delays or other losses, any of which (or a combination of which) could have a material adverse effect on our results of operations, financial condition and cash flows.

The COVID-19 pandemic has impacted global economic activity, caused significant volatility and negative pressure in financial markets and reduced the demand for energy in our service territory. In addition to reduced revenuesrevenue and lower margins resulting from decreased energy demand within our service territory in recent years, we have also have incurred expenses relating to COVID-19, including expenses relating to events outside of our control. In addition to contributing to economic slowdown or a recession, COVID-19 or another pandemic could have material and adverse effects on our results of operations, financial condition and cash flows due to, among other factors:

We will continue to review and modify our plans as conditions change. Despite our efforts to manage and remedy these impacts to us, their ultimateThe impact of the COVID-19 pandemic also depends on factors, beyond our knowledge or control, including the durationeffectiveness and severitytiming of this outbreakupdated vaccines to address new variants, the development of more virulent COVID-19 variants as well as third-party actions taken to contain its spread and mitigate its public health effects.

Our internal controls, accounting policies and practices and internal information systems are designed to enable us to capture and process transactions and information in a timely and accurate manner in compliance with GAAP in the United States of America, laws and regulations, taxation requirements and federal securities laws and regulations in order to, among other things, disclose and report financial and other information in connection with the recovery of our costs and with our reporting requirements under federal securities, tax and other laws and regulations and to properly process payments. We have also implemented corporate governance, internal control and accounting policies and procedures in connection with the Sarbanes-Oxley Act of 2002. Our internal controls and policies have been and continue to be closely monitored by management and our Board of Directors. While we believe these controls, policies, practices and systems are adequate to verify data integrity, unanticipatedthe identification of

significant deficiencies or material weaknesses in our internal controls due to shortfallsthat we cannot remediate in oversight or resource constraintsa timely manner could lead to improprieties and undetected errors that could result in material misstatements in our financial statements, the disallowance of cost recovery, noncompliant disclosure and reporting or incorrect payment processing. The consequences of these events could have a material adverse effect on our results of operations, financial condition and cash flows.

One of the challenges we face is to retain a skilled, efficient and cost-effective workforce while recruiting new talent to replace losses in knowledge and skills due to resignations, terminations or retirements. This undertaking could require us to make additional financial commitments and incur increased costs. If we are unable to successfully attract and retain an appropriately qualified workforce, it could have a material adverse effect on our results of operations, financial condition and cash flows. In addition, we have employee compensation plans that reward the performance of our employees. We seek to ensure that our compensation plans encourage acceptable levels for risk and high performance through pay mix, performance metrics and timing. We may not be able to successfully train new personnel as current workers with significant knowledge and expertise retire. We also may be unable to staff our business with qualified personnel in the event of significant absenteeism related to a pandemic illness. Excessive risk-taking by our employees to achieve performance targets, through mitigated by policies and procedures, could result in events that have a material adverse effect on our results of operations, financial condition and cash flows.

We are subject to collective bargaining agreements with employees who are members of a union. Over half of our employees are represented by a collective bargaining agreement. While we believe that we maintain a satisfactory relationship with our employees, it is possible that labor disruptions affecting some or all of our operations could occur during the period of the collective bargaining agreement or at the expiration of the collective bargaining agreement before a new agreement is negotiated. Work stoppages by, or poor relations or ineffective negotiations with, our employees or other workforce issues could have a material adverse effect on our results of operations, financial condition and cash flows.

From time to time, we use non-derivative and derivative instruments, such as swaps, options, futures and forwards, to manage financial risks. These trades are affected by a range of factors, including fluctuations in interest rates and optimization opportunities. We have attempted to manage our risk exposure by establishing and enforcing risk limits and risk management policies. Despite our efforts, however, these risk limits and management policies may not work as planned and fluctuating prices and other events could adversely affect our results of operations, financial condition and cash flows. In the absence of actively quoted market prices and pricing information from external sources, the valuation of these instruments can involve management’s judgment or the use of estimates. As a result, changes in the underlying assumptions or use of alternative valuation methods could affect the reported fair value of some of these contracts. We could also recognize financial losses as a result of volatility in the market values of these contracts, a counterparty failing to perform or the underlying transactions which the instruments are intended to hedge failing to materialize, which could result in a material adverse effect on our results of operations, financial condition and cash flows.

We operate in a highly regulated industry that requires the continued operation of sophisticated systems and network infrastructure at our transmission, distribution and other facilities. We also use various financial, accounting and other systems in our businesses. These systems and facilities are vulnerable to unauthorized access due to hacking, viruses, other cybersecurity attacks and other causes and also may be subject to acts of sabotage and vandalism. In particular, given the importance of energy and the electric grid, there is the possibility that our systems

and facilities could be targets of terrorism or acts of war, and there has been an increased focus on the U.S. energy grid that is believed to be related to the Russia/Ukraine conflict. We have implemented measures to help prevent unauthorized access to our systems and facilities, including network and system monitoring, identification and deployment of secure technologies and certain other measures to comply with mandatory regulatory reliability standards. Pursuant to NERC requirements, we have a robust cybersecurity plan in place and are subject to regular audits by an independent auditor approved by NERC. We routinely test our systems and facilities against these regulatory requirements in order to measure compliance, assess potential security risks and identify areas for improvement. In addition, we provide cybersecurity training for our employees and perform exercises designed to raise employee awareness of cyberriskscyber risks on a regular basis. To date, cyberattacks on our business and operations have not had a material impact on our operations or financial results. Despite these efforts, if our systems or facilities were to be breached or disabled, we may be unable to recover them in a timely manner to fulfill critical business functions, including the supply of electric services to our customers, and we could experience decreases in revenuesrevenue and increases in costs that could materially and adversely affect our results of operations, financial condition and cash flows.

In the course of our business, we also store and use customer, employee and other personal information and other confidential and sensitive information, including personally identifiable information and personal financial information. If our or our third-party vendors’ systems were to be breached or disabled, sensitive and confidential information and other data could be compromised, which could result in liability or penalties under privacy laws, negative publicity, remediation costs and potential litigation, damages, consent orders, injunctions, fines and other relief.

To help mitigate these risks, we maintain insurance coverage against some, but not all, potential losses, including coverage for illegal acts against us. However, insurance may not be adequate to protect us against all costs and liabilities associated with these risks.

In Ohio, transmission and distribution businesses are regulated. Even though rate regulation is premised on full recovery of prudently incurred costs and a reasonable rate of return on invested capital, there can be no assurance that the PUCO will agree that all of our costs have been prudently incurred or are recoverable. There can be no assurance that the regulatory process in which rates are determined will always result in rates that will produce a full or timely recovery of our costs or permitted rates of return. Accordingly, the revenue AES Ohio receives may or may not match its expenses at any given time.

Changes in or reinterpretations of, or the unexpected application of the laws, rules, policies and procedures that set or govern electric rates, permitted rates of return, rate structures, operation of a competitive bid structure to supply retail generation service to SSO customers, reliability initiatives, capital expenditures and investments and the recovery of these and other costs on a full or timely basis through rates, power market prices and the frequency and timing of rate increases, could have a material adverse effect on our results of operations, financial condition and cash flows.

The renewable energy standards have increased our costs and are expected to continue to increase (and could materially increase) these costs. AES Ohio is currently entitled to recover costs associated with its renewable energy compliance. If, in the future, we are unable to timely or fully recover these costs, it could have a material

We are subject to various federal, state, regional and local environmental protection and health and safety laws and regulations governing, among other things, the remediation of retired generation and other facilities, storage, handling, use, storage, disposal and transportation of coal combustion residuals and other materials, some of which may be defined as hazardous materials, the emission and discharge of hazardous and other materials or items into the environment, such as GHGs; and the health and safety of our employees. Such laws, rules and regulations can become stricter over time, and we could also become subject to additional environmental laws, rules and regulations and other requirements in the future. Environmental laws, rules and regulations also require us to comply with inspections and obtain and comply with a wide variety of environmental licenses, permits, inspections and other governmental authorizations. These laws, rules and regulations often require a lengthy and complex process of obtaining and renewing licenses, permits and other governmental authorizations from federal, state and local agencies. If we are not able to timely comply with inspections and obtain, maintain or comply with all environmental laws, rules and regulations and all licenses, permits and other government authorizations required to operate our business, then our operations could be prevented, delayed or subject to additional costs. A violation of environmental laws, rules, regulations, licenses, permits or other requirements can result in substantial fines, penalties, other sanctions, permit revocation, facility shutdowns, the imposition of stricter environmental standards and controls or other injunctive measures affecting operating assets. In addition, any actual or alleged violation of these laws, rules or regulations and other requirements may require us to expend significant resources to defend against any such actual or alleged violations. AES Ohio has an ownership interest in OVEC, which operates generating stations. We generally are responsible for our respective pro rata share of expenditures for complying with environmental laws, rules, regulations, licenses, permits and other requirements at this generating station, but have limited control over the compliance measures taken by the operator. Under certain environmental laws, we could also be held strictly, jointly and severally responsible for costs relating to contamination at our past or present facilities and at third-party waste disposal sites. We could also be held liable for human exposure to such hazardous substances or for other environmental damage.

In particular, we are subject to potentially significant remediation expenses, enforcement initiatives, private-party lawsuits and reputational risk associated with CCR, which consists of bottom ash, fly ash, boiler slag and flue gas desulfurization materials generated from burning coal generated at our formerly owned coal-fired generation plant sites. CCR currently remains onsite at OVEC's facilities, including in CCR ponds. Compliance with the CCR rule, amendments to the federal CCR rule, or other federal, state, or foreign rules or programs addressing CCR may require us to incur substantial costs. In addition, CCR, particularly with respect to its beneficial use and regulation as nonhazardous solid waste, has been the subject of interest from environmental non-governmental organizations and the media. Any of the foregoing could have a material adverse effect on our results of operations, financial condition and cash flows.

In December 2015, the parties to the United Nations Framework Convention on Climate Change convened for the 21st Conference of the parties and the resulting Paris Agreement established a long-term goal of keeping the increase in global average temperature well below 2°C above pre-industrial levels. We anticipate that the Paris Agreement will continue the trend toward efforts to de-carbonize the global economy. Although the U.S. was officially able to withdraw from the Paris Agreement on November 4, 2020, on January 20, 2021, President Biden began the 30-day process of rejoining the Paris Agreement, which became effective for the U.S. on February 19, 2021. In November 2022,2023, the international community gathered for COP28. The Parties agreed to non-binding language calling on countries to transition away from fossil fuels in Egypt at the 27th Conferenceenergy systems to the Parties on the UN Framework Convention on Climate Change (COP27), during which certain countries reaffirmed commitments associated with the Paris Agreement and a fund for loss and damage associated with climate change was announced.achieve net zero emissions by 2050.

Any existing or future international, federal, state or regional legislation or regulation of GHG emissions, to the extent directly or indirectly applicable to our electric transmission and distribution operations, could have a material adverse impact on our financial performance.

Furthermore, according to the Intergovernmental Panel on Climate Change, physical risks from climate change could include, but are not limited to, increased runoff and earlier spring peak discharge in many glacier and snow-fed rivers, warming of lakes and rivers, an increase in sea level, changes and variability in precipitation and in the intensity and frequency of extreme weather events. Physical impacts may have the potential to significantly affect our business and operations. For example, extreme weather events could result in increased downtime and operation and maintenance costs at our electric power transmission and distribution assets and facilities. Variations in weather conditions, primarily temperature and humidity, would also be expected to affect the energy needs of customers. A decrease in energy consumption could decrease our revenues.revenue. In addition, while revenuesrevenue would be expected to increase if the energy consumption of customers increased, such increase could prompt the need for additional investment in generation capacity.

As an owner of a bulk power transmission system, AES Ohio is subject to mandatory reliability standards promulgated by the NERC and enforced by the FERC. The standards are based on the functions that need to be performed to ensure the bulk power system operates reliably and is guided by reliability and market interface principles. In addition, AES Ohio is subject to Ohio reliability standards and targets. Compliance with reliability standards may subject us to higher operating costs or increased capital expenditures. Although we expect to recover costs and expenditures from customers through regulated rates, there can be no assurance that the PUCO will approve full recovery in a timely manner. If we were found not to be in compliance with the mandatory reliability

standards, we could be subject to sanctions, including substantial monetary penalties, which could have a material adverse effect on our results of operations, financial condition and cash flows.

We are subject to extensive regulation at the federal, state, and local levels. For example, at the federal level, AES Ohio is regulated by the FERC and the NERC and, at the state level, by the PUCO. The regulatory power of the PUCO over AES Ohio is both comprehensive and typical of the traditional form of regulation generally imposed by state public utility commissions. We face the risk of unexpected or adverse regulatory action. Regulatory discretion is reasonably broad in Ohio. AES Ohio is subject to regulation by the PUCO as to our services and facilities, the valuation of property, the construction, purchase, or lease of electric facilities, the classification of accounts, rates of depreciation, the increase or decrease in retail rates and charges, the issuance of securities and incurrence of debt, the acquisition and sale of some public utility properties or securities and certain other matters. As a result of the

We are subject to the tax laws and regulations of the U.S. federal, state and local governments. From time to time, legislative measures may be enacted that could adversely affect our overall tax positions regarding income or other taxes. There can be no assurance that our effective tax rate or tax payments will not be adversely affected by these legislative measures.

In addition, U.S. federal, state and local tax laws and regulations are extremely complex and subject to varying interpretations. There can be no assurance that our tax positions will be sustained if challenged by relevant tax authorities and if not sustained, there could be a material adverse effect on our results of operations, financial condition and cash flows.

As of December 31, 2022,2023, the carrying value of DPL's debt was $1,690.9$1,852.6 million and the carrying value of AES Ohio's debt was $832.7$1,027.5 million. Of AES Ohio's indebtedness, there was $705.0$1,005.0 million of First Mortgage Bonds as of December 31, 2022,2023, which are secured by the pledge of substantially all of the assets of AES Ohio under the terms of AES Ohio’s First and Refunding Mortgage. DPL's revolving credit facility is also secured by a pledge of common stock that DPL owns in AES Ohio. This level of indebtedness and related security has important consequences, including:

DPL and AES Ohio havehas variable rate debt that bears interest based on a prevailing rate that is reset based on a market index that can be affected by market demand, supply, market interest rates and other market conditions. We also maintain both cash on deposit and investments in cash equivalents from time to time that could be impacted by interest rate fluctuations. As such, any event which impacts market interest rates could have a material effect on our results of operations, financial condition and cash flows. In addition, rating agencies issue ratings on our credit and our debt that affect our borrowing costs under our financial arrangements and affect our potential pool of investors and funding sources. Credit ratings also govern the collateral provisions of certain of our contracts. If rating agencies downgrade our credit ratings, further, our borrowing costs would likely further increase, our potential pool of investors and funding resources could be reduced, and we could be required to post additional collateral under select contracts. These events would likely reduce our liquidity and profitability and could have a material adverse effect on our results of operations, financial condition and cash flows.

All of AES Ohio’s common stock is owned by DPL, and DPL is an indirectly wholly owned subsidiary of AES. Due to our relationship with AES, any adverse developments and announcements concerning AES may impair our ability to access the capital markets and to otherwise conduct business. In particular, downgrades in AES’s credit ratings could result in DPL’s or AES Ohio’s credit ratings being downgraded.

None.

Our executive offices are located at 1065 Woodman Drive, Dayton, Ohio. This facility and the remainder of our material properties are owned directly by AES Ohio. These properties include our distribution service center in Dayton, Ohio, various substations and other transmission and distribution equipment and property.

Not applicable.

All of the outstanding common stock of DPL is owned indirectly by AES and directly by a wholly-owned subsidiary of AES. As a result, DPL’s stock is not listed for trading on any stock exchange. AES Ohio’s common stock is held solely by DPL. As a result, DPL and as a result,AES Ohio stock is not listed for trading on any stock exchange.

During the years ended December 31, 2023, 2022 2021 and 2020,2021, DPL paid no dividendsdistributions to AES. AES Ohio declares and pays dividendsdistributions on its common shares to its parent DPL from time to time as declared by the AES Ohio Board of Directors. Return of capital paymentsDuring the years ended December 31, 2023 and dividends were2022, AES Ohio declared and paid in the amount ofdistributions totaling $83.0 million and $64.0 million, in the year ended December 31, 2022, declared in the amount of $42.0 million and paid in the amount of $52.0 million inrespectively. During the year ended December 31, 2021, andAES Ohio declared in the amountdistributions of $52.7$42.0 million and paid in the amountdistributions of $42.7 million in the year ended December 31, 2020.$52.0 million.

Our objective is to optimize AES Ohio’s performance in the U.S. utility industry by focusing on the following areas: safety, operations (reliability and customer satisfaction), financial and enterprise-wide performance (efficiency and cost savings, talent management/people, capital allocation/sustainability and corporate social responsibility). We set and measure these objectives carefully, balancing them in a way and to a degree necessary to ensure a sustainable

high level of performance in these areas simultaneously compared to our peers. We monitor our performance in these areas, and where practical and meaningful, compare performance in some areas to peer utilities. Because some of our financial and enterprise-wide performance measures are company-specific performance goals, they are not benchmarked.

Our safety performance is measured by both leading and lagging metrics. Our leading safety metrics track safety observations, safety meeting engagement and the reporting of non-injury significant injury potential incidents.lost time incident ("LTI") rates for our employees and contractors based on OSHA standards. Our lagging safety metrics track lost workday cases, severity rate, and recordable incidents. We are committed to excellence in safety and have implemented various programs to increase safety awareness and improve work practices.

AES Ohio measures delivery reliability by Customer Average Interruption Duration Index ("CAIDI"), System Average Interruption Duration Index ("SAIDI") and System Average Interruption Frequency Index ("SAIFI") and benchmarks the reliability metrics against other utilities at both the state and national levels. AES Ohio also measures customer centricity on more of an individual basis by the industry metric of Customers that Experience Multiple Interruption of five or more times (“CEMI-5”). We measure customer satisfaction using Research America Utilities Market Research - Consumer Insight. Monitoring performance in the areas such as competitive rates, operational reliability and customer service supports our ongoing work to deliver reliable service to our customers.

Compared with the prior year, DPL's results for the year ended December 31, 20222023 reflect a decreasean increase in income / (loss) from continuing operations before income tax of $36.7$56.6 million, or 164%396%, primarily due to factors including, but not limited to:

Compared with the prior year, AES Ohio's results for the year ended December 31, 20222023 reflect a decreasean increase in income from continuing operations before income tax of $37.0$59.1 million, or 70%374%, primarily due to factors including, but not limited to:

DPL's and AES Ohio's electric sales and billed customers were as follows: