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Market tone was the main drag in the second quarter

US filtration products maker Atmus Filtration Technologies was among the stocks that hurt portfolio performance in Riverwater Partners’ investor letter for the second quarter of 2026. The fund manager said signals from the freight transportation market had become mixed, expectations for new truck production had weakened and margin pressure was weighing on investor sentiment.

The engine filtration business, spun off from Cummins, is best known for its Fleetguard brand. Riverwater Partners said it reduced its weighting in the stock to a neutral level during the quarter because of the shift in outlook, while still describing the company’s core aftermarket-driven business model as resilient.

What do the share performance and valuation figures show?

Key market data

According to the figures in the source, Atmus shares fell by about 10% in the second quarter. At the August 31, 2026 close, the stock price stood at $47.23; over the past month, losses reached 14.31%, while the return over the past 52 weeks was calculated at 5.47%.

  • Share price: $47.23
  • Market value: $3.85 billion
  • 52-week range: $42.60-$66.50
  • Past 1 month: down 14.31%
  • Past 52 weeks: up 5.47%

This picture shows selling pressure dominating in the short term, even though the stock remains positive on an annual basis. The decline from the 52-week high suggests the market is pricing in a more cautious view of growth and profitability.

Fund interest eased, but operating signals remain positive

Institutional interest in Atmus also softened by the end of the second quarter. According to the database, the number of hedge funds holding positions in the company fell to 25, down from 39 in the previous quarter.

Even so, the overall picture is not entirely negative for the company. The source also says Atmus posted record sales in the second quarter and raised its full-year revenue guidance. That suggests the market pressure appears to be driven more by the freight cycle, the outlook for new truck production and concerns over margins than by the company’s operating performance.

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