10 Best Small-Cap Data Center Cooling Stocks to Buy

In this article, we look at the 10 Best Small-Cap Data Center Cooling Stocks to Buy.

Data center cooling has moved from a back-office efficiency issue to one of the core constraints around AI infrastructure. Higher-density GPU servers are pushing more heat into smaller footprints, making conventional air-cooling systems less suitable for the most demanding facilities. ASHRAE’s 2026 AI Data Center Energy Performance Framework points to direct-to-chip cooling, rear-door heat exchangers, and immersion cooling as key thermal approaches for denser AI environments, with direct-to-chip systems supporting warm-water cooling and more hours of economized operation.

The investment case is also being shaped by scale. MarketsandMarkets places the global data center liquid cooling market at $4.07 billion in 2026 and projects it to reach $27.65 billion by 2033, implying a 31.5% compound annual growth rate. Its separate direct-to-chip cooling outlook projects the market to grow from $3.33 billion in 2026 to $17.31 billion by 2032. Strategic activity has followed the same direction, with Ecolab agreeing in March 2026 to acquire CoolIT Systems for about $4.75 billion in cash. The deal underscored how liquid cooling, thermal design, water efficiency, and facility-level energy management are becoming increasingly important parts of the AI data center buildout.

Methodology

For this article, we screened for U.S.-traded stocks with market caps between $250 million and $2 billion that have explicit exposure to data center cooling, thermal management, or the infrastructure systems that support heat removal in high-density data centers. Since the public small-cap market has few pure-play data center cooling companies, the screen was expanded to include companies operating in clearly related parts of the value chain. We then ranked the stocks by the number of hedge funds holding a stake in them as of Q1 2026 and limited the final selection to companies with recent news or business developments.

Why are we interested in the stocks that hedge funds pile into? The reason is simple: our research has shown that we can outperform the market by imitating the top stock picks of the best hedge funds. Insider Monkey’s quarterly newsletter’s strategy selects 14 small-cap and large-cap stocks every quarter and has returned 599.2% since May 2014, beating its benchmark by 372 percentage points (see more details here).

10. TSS, Inc. (NASDAQ:TSSI)

Number of Hedge Funds: 14

TSS, Inc. (NASDAQ:TSSI) is one of the best small-cap data center cooling stocks to Buy. After a June 4 announcement, TSS management presented at Singular Research’s one-on-one invitational conference on June 15 and at the Planet MicroCap Las Vegas investor conference on June 17, with one-on-one meetings available on June 17 and June 18. The recent investor outreach came as the company’s operating exposure remains closely tied to AI infrastructure deployment.

TSS provides rack and systems integration, procurement, deployment, configuration management, and modular data-center services for advanced computing customers. Its rack integration business specializes in advanced AI and Direct Liquid Cooling technologies, covering assembly, integration, and testing before deployment. The company also said a prior facility expansion would more than triple capacity to test and validate direct liquid-cooled racks, with added power and cooling capacity for rack testing stations. That gives TSS a direct role in the infrastructure layer needed to move liquid-cooled AI systems from design into operating data centers.

TSS, Inc. provides data-center services, rack and systems integration, procurement, deployment, configuration management, and modular data-center solutions for AI, high-performance computing, and digital infrastructure customers.

9. Graham Corporation (NYSE:GHM)

Number of Hedge Funds: 17

Graham Corporation (NYSE:GHM) is one of the best small-cap data center cooling stocks to Buy. On June 8, Graham reported fiscal fourth-quarter net sales of $67.1 million, up 13%, and full-year net sales of $245.3 million, up 17%. The more relevant point for a data-center cooling screen is not a direct hyperscale contract, but the company’s position in mission-critical fluid and heat-transfer equipment, a layer that sits close to the thermal-management problem as AI facilities move toward higher-density racks, warm-water loops, and more complex heat rejection.

Graham ended fiscal 2026 with a record backlog of $532.6 million, up 29%, and record full-year orders of $359.4 million, giving the business a healthier demand base than a narrow cooling concept stock. Management also said capital spending focused on capability and capacity expansion, automation, productivity improvements, and advanced manufacturing, which is relevant for customized engineered systems. The stock fits the list as a selective thermal-infrastructure play, not as a pure liquid-cooling vendor.

Graham Corporation designs and manufactures mission-critical fluid, power, heat transfer, vacuum, and advanced mixing technologies for the defense, energy, process, and space markets.

8. New Era Energy & Digital, Inc. (NASDAQ:NUAI)

Number of Hedge Funds: 17

New Era Energy & Digital, Inc. is one of the best small-cap data center cooling stocks to Buy. On May 28, New Era Energy & Digital announced a pending agreement that would lead to the dismissal of the company from the State of New Mexico’s lawsuit tied to legacy helium and gas assets. The company said the settlement does not include any admission of liability and that it remains focused on advancing its AI data-center strategy.

The development is relevant because New Era is still an early-stage, high-risk infrastructure developer, so legal and balance-sheet clarity matter for execution. Its cooling exposure comes through Texas Critical Data Centers, a 438-acre AI and high-performance computing campus near Odessa, Texas. New Era describes the project as a large-scale, phased development built around powered land, powered shells, flexible behind-the-meter power, water efficiency, and modular data-center deployment. That gives the stock a speculative site-development angle tied to the power, water, and thermal constraints around AI infrastructure.

New Era Energy & Digital, Inc. develops next-generation digital infrastructure and integrated power assets, including large-scale AI and high-performance computing data-center campuses in energy-rich U.S. markets.

7. AirJoule Technologies Corporation (NASDAQ:AIRJ)

Number of Hedge Funds: 18

AirJoule Technologies Corporation (NASDAQ:AIRJ) is one of the best small-cap data center cooling stocks to Buy. On May 28, AirJoule Technologies announced a $15.0 million registered direct offering of common stock, with net proceeds intended to support commercialization of its AirJoule Core and AirJoule Prime systems. The company said the raise, combined with existing cash, is expected to fund operations into 2028, which is important because AirJoule remains an early-stage commercialization story rather than an established equipment supplier. Its data-center relevance comes from using low-grade waste heat from air-cooled and liquid-cooled facilities to produce distilled water from air. AirJoule says that water can support evaporative cooling, closed-loop system losses, onsite operations, and broader water-efficiency needs.

The company also says its system releases dehumidified air and can reduce thermal cooling demand before residual heat reaches rooftop chillers. That gives the stock a direct but speculative angle on the cooling and water constraints around high-density AI data centers.

AirJoule Technologies Corporation develops atmospheric water harvesting and sorption-based systems through partnerships including GE Vernova and Carrier Global Corporation.

6. Bowman Consulting Group Ltd. (NASDAQ:BWMN)

Number of Hedge Funds: 19

Bowman Consulting Group Ltd. (NASDAQ:BWMN) is one of the best small-cap data center cooling stocks to Buy. On June 24, Bowman secured $11.2 million in new U.S. Department of Agriculture aerial mapping awards under the PINE Blanket Purchase Agreement. The three awards cover aerial data acquisition and processing across 38 states, including about 8.3 million acres of National Resources Inventory sites and 3.8 million Stewardship Lands Inventory easement acres.

The cooling link sits in Bowman’s broader data-center engineering platform rather than in the USDA work itself. High-resolution geospatial data, site surveying, utility planning, water-resource engineering, mechanical systems, and permitting are all important pieces of data-center campus development, especially as AI facilities require more power, water coordination, and thermal infrastructure. Bowman says its mission-critical team supports data-center designs above 250 kW per cabinet and includes mechanical cooling systems, CFD analysis, CDU and heat-exchanger designs, and direct liquid cooling capabilities today.

Bowman Consulting Group Ltd. is a national engineering services and program management firm serving infrastructure, building, energy, environmental, and mission-critical markets.

5. Limbach Holdings, Inc. (NASDAQ:LMB)

Number of Hedge Funds: 21

Limbach Holdings, Inc. (NASDAQ:LMB) is one of the best small-cap data center cooling stocks to Buy. On June 18, Limbach highlighted modular construction solutions for data centers, positioning its prefabrication and MEPC platform around faster delivery of mission-critical infrastructure. The company said it supports owners with utility plants, mechanical skids, equipment modules, prefabricated piping systems, design-assist work, BIM coordination, virtual construction, constructability reviews, logistics planning, commissioning, startup, and Day 2 operations.

The cooling relevance is direct enough for a small-cap screen because Limbach’s data-center work includes HVAC, mechanical systems, plumbing, electrical infrastructure, and controls, all of which sit around heat removal and uptime. As AI facilities push higher rack density, modular mechanical systems and prefabricated piping can help reduce on-site complexity and speed deployment of cooling-support infrastructure. Limbach also says its approach helps data-center owners maintain uptime, increase density, and scale facilities more efficiently, giving the stock a services-level angle on thermal infrastructure.

Limbach Holdings, Inc. designs, installs, manages, services, and maintains HVAC, mechanical, electrical, plumbing, and control systems for mission-critical facilities, including data centers.

4. Ameresco, Inc. (NYSE:AMRC)

Number of Hedge Funds: 22

Ameresco, Inc. (NYSE:AMRC) is one of the best small-cap data center cooling stocks to Buy. On June 23, Ameresco announced two Advanced Metering Infrastructure contracts with Baytown and Shenandoah, Texas, representing more than $5 million in combined investment. The projects will modernize water metering infrastructure with near real-time usage data, hourly consumption visibility, faster leak detection, and integration with each city’s utility billing platform.

This is not a direct data-center cooling contract, but it is still relevant to the cooling side of AI infrastructure because water efficiency is becoming a practical constraint for large, heat-intensive facilities. Ameresco already serves data centers through energy infrastructure and efficiency work, and its water-management capabilities add another layer to that positioning. The Texas contracts show a municipal-scale use case for reducing water loss and improving system visibility, the same type of operating discipline that becomes more important as cooling demand rises around power-dense data centers.

Ameresco, Inc. provides energy efficiency, infrastructure modernization, distributed energy, and decarbonization solutions for public, commercial, industrial, utility, and data-center customers.

3. CTS Corporation (NYSE:CTS)

Number of Hedge Funds: 23

CTS Corporation (NYSE:CTS) is one of the best small-cap data center cooling stocks to Buy. On June 16, CTS introduced the TSX Crystal with Integrated Thermistor, its first crystal product to place a thermistor inside the package. The product is not a cooling unit, but it fits the thermal-management layer around dense electronic systems: it gives real-time temperature feedback close to the crystal element, helping designers improve frequency compensation across wider operating temperatures while reducing board-level complexity.

CTS said the TSX series supports frequencies from 16 MHz to 285 MHz, with stability options ranging from ±10 ppm to ±50 ppm over temperature, and targets applications including network synchronization, routers, and switches. The data-center connection is also broader than this single launch. CTS markets temperature sensors for server racks, cooling systems, and airflow-management zones, where precise thermal monitoring helps prevent overheating and supports higher rack density. That gives the stock a sensor-level exposure to the cooling efficiency problem created by AI infrastructure.

CTS Corporation designs and manufactures sensors, actuators, and electronic components for industrial, aerospace/defense, medical, transportation, and other end markets.

2. Willdan Group, Inc. (NASDAQ:WLDN)

Number of Hedge Funds: 31

Willdan Group, Inc. (NASDAQ:WLDN) is one of the best small-cap data center cooling stocks to Buy. On June 1, Willdan released its June investor presentation, highlighting data-center siting and load forecasting, substation and grid design, building and energy-efficiency upgrades, and infrastructure construction support as parts of its integrated consulting, engineering, and implementation platform. The data-center cooling angle comes through efficiency and systems optimization rather than direct liquid-cooling hardware. Willdan says it works with mission-critical campuses where power and heat interact, and its data-center services include engineering, energy assessments, controls integration, procurement, and construction management.

The company also cites data-center projects where it optimized cooling systems, adjusted setpoints, improved controls, and reduced energy use, including an Evoque Data Centers project that generated 1.5 million kWh of annual savings. In AI data centers, cooling and power are increasingly connected operating constraints, so Willdan’s work in energy efficiency, utility interconnection, load forecasting, and facility systems gives it practical services-level exposure to the thermal-management problem.

Willdan Group, Inc. provides technical, engineering, energy-efficiency, infrastructure, and consulting services to utilities, public agencies, and commercial and industrial customers.

1. TIC Solutions, Inc. (NYSE:TIC)

Number of Hedge Funds: 32

TIC Solutions, Inc. (NYSE:TIC) is one of the best small-cap data center cooling stocks to Buy. On June 1, TIC Solutions announced a repricing of its term loan, a financing move the company said would lower annual cash interest expense by about $4 million and improve financial flexibility. The development gives the company more room to support an expanded platform that now includes engineering, testing, inspection, certification, and asset-integrity services.

For the data-center cooling theme, TIC fits through the engineering and reliability layer rather than through direct liquid-cooling equipment. High-density AI facilities need better planning around heat rejection, airflow, commissioning, equipment placement, and building-systems performance, especially as rack power rises and cooling systems become more complex. TIC’s broader asset-lifecycle model gives it exposure to those infrastructure demands, making the stock a mission-critical services play tied to thermal reliability and data-center operating performance.

TIC Solutions, Inc. provides tech-enabled asset integrity, engineering, geospatial, testing, inspection, certification, and compliance services for industrial, infrastructure, commercial, utility, and public-sector markets.

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