William Blair Investment Management
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William Blair Investment Management’s Atmus Filtration Technologies ATMU Stock Holding History

William Blair Investment Management’s Portfolio ATMU Stock Details ATMU Fund Activity
Bought
Maintained
Sold
Quarter Market Value Status Shares Change in
Stake 		Trade Value Portfolio Weight Portfolio Position
2026
Q1 		$24.2M Sell
426,072
-255,900
-38% -$15.1M 0.08% 232
2025
Q4 		$35.4M Sell
681,972
-69,785
-9% -$3.38M 0.1% 176
2025
Q3 		$33.9M Sell
751,757
-45,526
-6% -$1.91M 0.09% 189
2025
Q2 		$29M Sell
797,283
-62,808
-7% -$2.24M 0.08% 222
2025
Q1 		$31.6M Buy
+860,091
New +$33.9M 0.09% 209

Other funds holding ATMU

BlackRock
BlackRock New York $5.72T AUM 30.48% 1-Year Est. Return
Fidelity Investments
Fidelity Investments Boston, Massachusetts $1.9T AUM 41.92% 1-Year Est. Return
T. Rowe Price Associates
T. Rowe Price Associates Baltimore, Maryland $865B AUM 30.76% 1-Year Est. Return
VPM
Vanguard Portfolio Management Malvern, Pennsylvania $1.91T AUM
VCM
Vanguard Capital Management Malvern, Pennsylvania $4.04T AUM
Invesco
Invesco Atlanta, Georgia $1.02T AUM 30.18% 1-Year Est. Return
Goldman Sachs
Goldman Sachs New York $871B AUM 31.28% 1-Year Est. Return
Geode Capital Management
Geode Capital Management Boston, Massachusetts $1.61T AUM 30.72% 1-Year Est. Return
First Trust Advisors
First Trust Advisors Wheaton, Illinois $140B AUM 27.84% 1-Year Est. Return
State Street
State Street Boston, Massachusetts $2.9T AUM 29.55% 1-Year Est. Return

William Blair Investment Management's ATMU Position: Q1 2026 in Review

William Blair Investment Management reduced its Atmus Filtration Technologies (ATMU) stake by 38% in Q1 2026, selling an estimated $15.1M and leaving 426,072 shares worth $24.2M. The position accounts for 0.08% of the portfolio, ranked #232.

William Blair Investment Management first reported a position in ATMU in Q1 2025 and has held it in 5 quarters since. The position peaked at $35.4M in Q4 2025. 351 funds tracked by Wall St. Rank hold ATMU as of Q1 2026.

  • William Blair Investment Management held 426,072 shares of Atmus Filtration Technologies worth $24.2M as of Q1 2026.
  • William Blair Investment Management sold 255,900 Atmus Filtration Technologies shares in Q1 2026, an estimated $15.1M.
  • Atmus Filtration Technologies made up 0.08% of William Blair Investment Management's portfolio in Q1 2026, its #232 holding.
  • William Blair Investment Management first reported a position in Atmus Filtration Technologies in Q1 2025 and has held it in 5 quarters since.
  • William Blair Investment Management's Atmus Filtration Technologies position peaked at $35.4M in Q4 2025.
  • 351 funds tracked by Wall St. Rank held Atmus Filtration Technologies as of Q1 2026.

Based on William Blair Investment Management's 13F filing for Q1 2026, filed 8 May 2026.