Port Capital Doubles Down on Atmus Filtration Technologies Stock, Buys Another $22 Million in Shares

What happened

According to a filing with the Securities and Exchange Commission dated Feb. 17, 2026, Port Capital LLC increased its stake in Atmus Filtration Technologies (ATMU +1.85%) by 446,260 shares. The estimated transaction value was $21.60 million, based on the average quarterly closing price. The value of the position at quarter-end rose by $26.10 million, which reflects both share purchases and price changes during the period.

What else to know

Port Capital added to its Atmus Filtration Technologies position, bringing its position to 1.96% of reported AUM.

• Top holdings after the filing:
  • Heico Class A Shares: $217.13 million (9.4% of AUM)
  • RBC Bearings: $165.85 million (7.2% of AUM)
  • Amphenol: $125.50 million (5.4% of AUM)
  • Teledyne Technology: $120.77 million (5.2% of AUM)
  • Ametek: $92.74 million (4.0% of AUM)

As of March 9, 2026, shares of Atmus Filtration Technologies were priced at $58.21, up 55.7% over the past year; one-year alpha versus the S&P 500 was 36 percentage points.

Company overview

Company snapshot

Atmus Filtration Technologies:

• Provides filtration products, including fuel, lube, air, hydraulic filters, crankcase ventilation systems, and coolants, primarily under the Fleetguard brand
• Generates revenue through the design, manufacture, and sale of filtration solutions for commercial vehicles and industrial equipment globally
• Serves original equipment manufacturers, dealers/distributors, and end-users across sectors such as transportation, agriculture, construction, mining, and power generation

Atmus Filtration Technologies is a leading provider of advanced filtration products and solutions, operating at scale with a global footprint and a diversified customer base. The company leverages its engineering expertise and established Fleetguard brand to deliver essential filtration technologies for demanding commercial and industrial applications. Its strategic focus on OEM relationships and aftermarket distribution supports stable recurring revenue and positions the business for continued growth in the industrial filtration market.

What this transaction means for investors

Atmus Filtration Technologies is a brand-new stock to me, and it was interesting to learn about, especially given Port Capital’s addition over the last two quarters. The company spun off from **Cummins **in 2023 and is the leader in its heavy-duty engine filtration niche. While we don’t know exactly what prompted Port Capital to buy Atmus in Q4, one reason that might’ve sparked excitement was the company’s $450 million acquisition of Koch Filter.

While it isn’t a massive acquisition size-wise, Koch is a leader in “air filtration solutions for growing end-markets, including industrial and commercial HVAC, data centers, and power generation.” This is a new area of business for Atmus and gives it access to the quickly growing data center and power generation industries, which continue to expand rapidly thanks to the ongoing AI boom, along with the electricity needed to fuel it.

In a way, Atmus is the perfect example of a HALO stock. HALO stands for “Heavy Assets, Low Obsolescence,” meaning its tangible products are less prone to disruption from AI. On the contrary, AI appears to be a tailwind for the company following its new acquisition, so I think Port Capital’s recent buys make a lot of sense. I’ll be keeping Atmus on my radar over the following quarters, as it is a promising, steady-Eddie, dividend stock with a solid base of recurring revenue streams. Trading at 20 times forward earnings, Atmus’s incremental sales growth isn’t outrageously priced.