NATURAL GAS SERVICES GROUP INC

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM 10-K

☒ ANNUAL REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934

For the fiscal year ended December 31, 2025

or

☐ TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934

For the transition period from________________________to__________________________

Commission file number:1-31398

(Exact Name of Registrant as Specified in its Charter)

Securities registered pursuant to section 12(g) of the Act: None.

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

Yes ☐No ☒

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

Yes ☐No ☒

Indicate by check mark whether the 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.

Yes ☒ No ☐

Indicate by check mark whether the Registrant has submitted electronically every Interactive Data File required to be submitted pursuant to Rule 405 of Regulation S-T (§232.405 of this chapter) during the preceding 12 months (or for such shorter period that the registrant was required to submit and post such files).

Yes ☒ No ☐

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 definition 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 the Registrant has filed a report on and attestation to its management’s assessment of the effectiveness of its internal control over financial reporting under Section 404(b) of the Sarbanes-Oxley Act (15 U.S.C. 7262(b)) by the registered public accounting firm that prepared or issued its audit report.☒

If securities are registered pursuant to Section 12(b) of the Act, indicate by check mark whether the financial statements of the Registrant included in the filing reflect the correction of an error to previously issued financial statements.☐

Indicate by check mark whether any of those error corrections are restatements that required a recovery analysis of incentive-based compensation received by any of the Registrant’s executive officers during the relevant recovery period pursuant to §240.10D-1(b).☐

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

Yes ☐ No☒

The aggregate market value of voting and non-voting common equity held by non-affiliates of the Registrant as of June 30, 2025, was approximately $181.9 million based on the closing price of the common stock on that date on the New York Stock Exchange.

At March 13, 2026, there were 12,587,628 shares of the Registrant’s common stock outstanding.

Documents Incorporated by Reference

Certain information called for in Items 10, 11, 12, 13 and 14 of Part III are incorporated by reference to the Registrant’s definitive proxy statement for the annual meeting of shareholders expected to be held on June 5, 2026.

SPECIAL NOTE REGARDING FORWARD-LOOKING STATEMENTS

This Annual Report on Form 10-K contains certain forward-looking statements, within the meaning of Section 27A of the Securities Act of 1933, as amended (the “Securities Act”), and Section 21E of the Securities Exchange Act of 1934, as amended (the “Exchange Act”), and information pertaining to us, our industry and the oil and gas industry that is based on the beliefs of our management, as well as assumptions made by and information currently available to our management. All statements, other than statements of historical facts contained in this Annual Report on Form 10-K, including statements regarding our future financial position, growth strategy, budgets, projected costs, plans and objectives of management for future operations, are forward-looking statements. We use the words “may,” “will,” “expect,” “anticipate,” “estimate,” “guidance,” “believe,” “continue,” “intend,” “plan,” “budget” and other similar words to identify forward-looking statements. You should read statements that contain these words carefully and should not place undue reliance on these statements because they discuss future expectations, contain projections of results of operations or of our financial condition and/or state other “forward-looking” information. We do not undertake any obligation to update or revise publicly any forward-looking statements. Although we believe our expectations reflected in these forward-looking statements are based on reasonable assumptions, no assurance can be given that these expectations or assumptions will prove to have been correct. Important factors that could cause actual results to differ materially from the expectations reflected in the forward-looking statements include, but are not limited to, the following factors and the other factors described in Part I, Item 1A. “Risk Factors” and Part II, Item 7.“Management’s Discussion and Analysis of Financial Condition and Results of Operations” of this Annual Report on Form 10-K:

•conditions in the oil and gas industry, including the supply and demand for oil and gas and volatility in the prices of oil and gas;

•changes in general economic and financial conditions, inflationary pressures, the potential for economic recession in the U.S., tariffs and trade restrictions, including the imposition of new and higher tariffs on imported goods and retaliatory tariffs implemented by other countries on U.S. goods, and the potential effects on our financial condition, results of operations and cash flows;

•our reliance on major customers;

•failure of projected organic growth due to adverse changes in the oil and gas industry, including depressed oil and gas prices, oppressive environmental regulations and competition;

•our inability to achieve increased utilization of assets, including rental fleet utilization and monetizing other non-cash balance sheet assets;

•failure of our customers to continue to rent equipment after expiration of the primary rental term;

•our ability to economically develop and deploy new technologies and services, including technology to comply with health and environmental laws and regulations;

•failure to achieve accretive financial results in connection with any acquisitions we may make;

•fluctuations in interest rates;

•our ability to make dividends, distributions and share repurchases;

•changes in regulation or prohibition of new well or current completion techniques;

•competition among the various providers of compression services and products;

•changes in safety, health and environmental regulations;

•changes in economic or political conditions in the markets in which we operate;

•the inherent risks associated with our operations, such as equipment defects, malfunctions, natural disasters and adverse changes in customer, employee and supplier relationships;

•our inability to comply with covenants in our debt agreements and the decreased financial flexibility associated with our debt;

•inability to finance our future capital requirements and availability of financing;

•cybersecurity threats, including increased use of artificial intelligence and other emerging technologies;

•capacity availability, costs and performance of our outsourced compressor fabrication providers and overall inflationary pressures;

•impacts of world events, such as acts of terrorism, the conflicts in Iran, Ukraine, Venezuela and in the greater Middle East, and significant economic disruptions and adverse consequences resulting from possible long-term effects of potential pandemics and other public health crises; and

•general economic conditions.

We believe that it is important to communicate our expectations of future performance to our investors. However, events may occur in the future that we are unable to accurately predict or that we are unable to control. When considering our forward-looking statements, you should keep in mind the risk factors and other cautionary statements in this Annual Report on Form 10-K.

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Glossary of Industry Terms

“basin” – A large, low-lying geological depression containing a complex of petroleum source rocks. The Permian Basin, within which we operate a substantial portion of our compressor fleet, is considered to be the largest petroleum producing basin in the United States (“U.S.”).

“compressor” – In the energy industry, a compressor is utilized to facilitate a mechanical process to increase the pressure of natural gas by reducing its volume so that it can be transported through gathering and pipeline systems, injected into a reservoir for storage or injected into a well to enhance the recovery of petroleum products, among other applications. Various forms of compressors are used in the energy industry including reciprocating and screw types, among others. Compressors can be powered by natural gas from the wellhead or electricity from a power grid.

“gas lift” – A production technique whereby natural gas is injected into a well to increase/improve the oil production.

“horsepower” – A unit of measurement for the power produced by an engine in a compressor unit. Horsepower is calculated by multiplying the amount of force (in pounds) by the speed (in feet per second). One horsepower is equivalent to the power necessary to move 550 pounds one foot in one second. We classify our compressor units as large, medium or small based on their horsepower. Our large horsepower compressor units are 400 horsepower or more, medium horsepower units are 200 to 399 horsepower and small horsepower units are below 200 horsepower.

“HPGL” – High pressure gas lift.

“LNG” – Liquified natural gas.

“oil shale” – Also referred to as tight oil, is petroleum that consists of light crude oil contained in petroleum-bearing formations of low-permeability, often shales or tight sandstones.

“OEM” – Original equipment manufacturer refers to the company that makes a product to be sold by another company under its own name. We have several key OEM vendors that provide critical components to our compressor units including Caterpillar, Cummins and Waukesha for engines, Ariel for compressor frames and FW Murphy for controls, among others.

“OPEC” – The Organization of Petroleum Exporting Countries. Through its actions, this organization has a significant impact on the determination of global crude oil prices.

“play” – A geological term that refers to a group of oil and gas prospects within the same region that are controlled by the same set of geological circumstances. Plays are generally considered “conventional” when the resources can be extracted through traditional vertical wells or “unconventional” whereby the resources are tightly bound to the rock (generally shales and sandstones) requiring specialized measures for extraction including directional or horizontal drilling and hydraulic fracturing.

“reciprocating compressors” – A reciprocating compressor is a positive displacement device which compresses gas and/or vapor by using a piston in a cylinder and a back-and-forth, or reciprocating, motion.

“screw compressors” – A positive displacement compressor used in low-pressure and vapor compression applications where two rotating rotors intermesh to create pockets of continuously decreasing volume, in which the gas is compressed and its pressure is increased.

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