Ticker · CUSIP 574795100

MASI

MASIMO CORP
Healthcare·Medical Devices
···Share
Holders (tracked)
17
Combined shares
3,188,259
Combined value
$386.91M
Last close
$178.29
Quarter
2025Q4
Tracked holders · last 8 quarters
+5 vs previous quarter over the last 8.
17122024Q12025Q4
Price is +46.9% vs the avg quarter-end implied price across tracked holders.

SEC event timeline

29 events
  1. Ron Baron (Baron Capital / BAMCO) trimmed2026-02-17
    −14,848 shares · 2025Q4
    13F
  2. Ken Griffin (Citadel Advisors) trimmed2026-02-17
    −44,698 shares · 2025Q4
    13F
  3. D.E. Shaw & Co. opened position2026-02-17
    +66,016 shares · 2025Q4
    13F
  4. AQR Capital Management added2026-02-17
    +1,060,292 shares · 2025Q4
    13F
  5. Andreas Halvorsen (Viking Global) trimmed2026-02-17
    −559,093 shares · 2025Q4
    13F
  6. Izzy Englander (Millennium Mgmt) added2026-02-17
    +171,834 shares · 2025Q4
    13F
  7. T. Rowe Price trimmed2026-02-17
    −301,352 shares · 2025Q4
    13F
  8. Wellington Management added2026-02-17
    +5,638 shares · 2025Q4
    13F
  9. Jeremy Grantham (GMO) trimmed2026-02-17
    −98,997 shares · 2025Q4
    13F
  10. Paul Tudor Jones (Tudor Investment) opened position2026-02-17
    +16,242 shares · 2025Q4
    13F
  11. Ray Dalio (Bridgewater Associates) trimmed2026-02-13
    −95 shares · 2025Q4
    13F
  12. Renaissance Technologies opened position2026-02-12
    +59,900 shares · 2025Q4
    13F
  13. Norges Bank (Norway SWF) opened position2026-02-10
    +377,421 shares · 2025Q4
    13F
  14. Mario Gabelli (GAMCO) trimmed2026-02-05
    −800 shares · 2025Q4
    13F
  15. First Eagle Investment Management opened position2026-02-04
    +28 shares · 2025Q4
    13F
  16. AQR Capital Management trimmed2025-11-14
    −19,222 shares · 2025Q3
    13F
  17. Izzy Englander (Millennium Mgmt) added2025-11-14
    +12,224 shares · 2025Q3
    13F
  18. Steve Cohen (Point72) exited2025-11-14
    −24,219 shares · 2025Q3
    13F
  19. Two Sigma Investments exited2025-11-14
    −15,465 shares · 2025Q3
    13F
  20. Andreas Halvorsen (Viking Global) added2025-11-14
    +306,007 shares · 2025Q3
    13F
  21. T. Rowe Price added2025-11-14
    +109,486 shares · 2025Q3
    13F
  22. Wellington Management trimmed2025-11-14
    −1,072 shares · 2025Q3
    13F
  23. Ron Baron (Baron Capital / BAMCO) added2025-11-14
    +4,158 shares · 2025Q3
    13F
  24. Renaissance Technologies exited2025-11-13
    −25,377 shares · 2025Q3
    13F
  25. Norges Bank (Norway SWF) exited2025-11-13
    −39,053 shares · 2025Q3
    13F
  26. Jeremy Grantham (GMO) added2025-11-13
    +2,259 shares · 2025Q3
    13F
  27. Ray Dalio (Bridgewater Associates) added2025-11-13
    +69 shares · 2025Q3
    13F
  28. Mario Gabelli (GAMCO) trimmed2025-11-12
    −700 shares · 2025Q3
    13F
  29. Norges Bank (Norway SWF) added2025-11-12
    +206,693 shares · 2024Q3
    13F

Insider activity

No insider transactions in the last 30 days.
View full insider history for MASI →
Follow-the-investor returns
If you'd copied each holder of MASI…
Cost basis inferred from 13F share-delta history. Sorted by % return on the position they're still holding.
InvestorFirst inCost basisReturnPosition value today
T. Rowe Price2016Q1$0.32+55596.9%$38.1M
Mario Gabelli (GAMCO)2016Q1$41.84+326.1%$14.8M
Renaissance Technologies2016Q1$106.54+67.3%$10.7M
D.E. Shaw & Co.2016Q1$125.43+42.1%$11.8M
Paul Tudor Jones (Tudor Investment)2016Q1$129.76+37.4%$2.9M
First Eagle Investment Management2025Q4$130.07+37.1%$5K
AQR Capital Management2016Q1$131.08+36.0%$194.6M
Ken Griffin (Citadel Advisors)2016Q1$131.22+35.9%$553K
Ken Griffin (Citadel Advisors)2016Q1$131.22+35.9%$553K
Ken Griffin (Citadel Advisors)2016Q1$131.22+35.9%$553K
Izzy Englander (Millennium Mgmt)2016Q1$131.95+35.1%$33.5M
Wellington Management2016Q1$146.84+21.4%$1.4M
Ron Baron (Baron Capital / BAMCO)2019Q3$151.01+18.1%$66.7M
Norges Bank (Norway SWF)2016Q1$156.43+14.0%$67.3M
Andreas Halvorsen (Viking Global)2025Q2$162.33+9.8%$91.7M
Jeremy Grantham (GMO)2016Q1$167.69+6.3%$25.6M
Ray Dalio (Bridgewater Associates)2020Q3$181.82-1.9%$289K

Who moved on this name in 2025Q4

13F transactions reported for the latest quarter, grouped by direction.
New positions5
Added to3
Trimmed7
Exited0
—

Institutional ownership over time

Distinct super-investors holding this ticker · combined dollar value, by quarter.
QuarterHoldersCombined value
2022Q1
18
$3.88B
2022Q2
18
$6.83B
2022Q3
18
$28.7M
2022Q4
15
$1.03B
2023Q1
17
$1.29B
2023Q2
16
$1.20B
2023Q3
15
$643.9M
2023Q4
12
$901.1M
2024Q1
12
$1.54B
2024Q2
16
$1.49B
2024Q3
18
$196.5M
2024Q4
14
$278.0M
2025Q1
14
$162.6M
2025Q2
16
$281.7M
2025Q3
12
$286.3M
2025Q4
17
$386.9M

Who owns MASI

17 super-investors · 2025Q4
Tracked stake
3.19M
shares
Combined value
$387M
% of shares outstanding
—
shares-out unknown
Quarter action mix
New5Added3Trim9
#ManagerSharesValue
1AQR Capital Management1.09M$142M
2Andreas Halvorsen
Viking Global
514.3K$67M
3Norges Bank
Norway SWF
377.4K$49M
4Ron Baron
Baron Capital / BAMCO
373.9K$49M
5Izzy Englander
Millennium Mgmt
188.0K$24M
6Jeremy Grantham
GMO
143.8K$19M
7Mario Gabelli
GAMCO
83.0K$11M
8D.E. Shaw & Co.66.0K$9M
9Renaissance Technologies59.9K$8M
10Ken Griffin
Citadel Advisors
43.1K$6M
11Paul Tudor Jones
Tudor Investment
16.2K$2M
12Wellington Management7.8K$1M
13Ken Griffin
Citadel Advisors
5.1K$663K
14Ken Griffin
Citadel Advisors
3.1K$403K
15Ray Dalio
Bridgewater Associates
1.6K$211K
16T. Rowe Price213.6K$28K
17First Eagle Investment Management28$4K

Recent moves

20 transactions
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