Westfield Capital Management
MASI

Westfield Capital Management’s Masimo MASI Stock Holding History

Westfield Capital Management’s Portfolio MASI Stock Details MASI Fund Activity
Bought
Maintained
Sold
Quarter Market Value Status Shares Change in
Stake 		Trade Value Portfolio Weight Portfolio Position
2026
Q1 		$60.7M Sell
341,229
-1,180,820
-78% -$185M 0.25% 123
2025
Q4 		$198M Buy
1,522,049
+102,799
+7% +$14.7M 0.82% 22
2025
Q3 		$209M Buy
1,419,250
+238,047
+20% +$36M 0.88% 22
2025
Q2 		$199M Buy
1,181,203
+509,724
+76% +$81.4M 0.83% 26
2025
Q1 		$112M Sell
671,479
-97,379
-13% -$16.9M 0.54% 51
2024
Q4 		$127M Sell
768,858
-625,198
-45% -$98.7M 0.55% 50
2024
Q3 		$186M Buy
1,394,056
+262,370
+23% +$30.4M 0.84% 23
2024
Q2 		$143M Buy
1,131,686
+445,586
+65% +$58.7M 0.7% 28
2024
Q1 		$101M Sell
686,100
-132,376
-16% -$17.1M 0.53% 53
2023
Q4 		$95.9M Buy
818,476
+214,795
+36% +$20M 0.56% 53
2023
Q3 		$52.9M Sell
603,681
-350,118
-37% -$40.8M 0.36% 110
2023
Q2 		$157M Buy
+953,799
New +$166M 1% 21
2021
Q2 		– Sell
-207,846
Closed -$47.7M – 255
2021
Q1 		$47.7M Sell
207,846
-29,597
-12% -$7.44M 0.3% 120
2020
Q4 		$63.7M Sell
237,443
-53,100
-18% -$13.2M 0.38% 88
2020
Q3 		$68.6M Sell
290,543
-13,184
-4% -$2.96M 0.44% 75
2020
Q2 		$69.2M Sell
303,727
-129,550
-30% -$28.4M 0.48% 69
2020
Q1 		$76.7M Sell
433,277
-2,548
-0.6% -$437K 0.68% 47
2019
Q4 		$68.9M Buy
435,825
+214,380
+97% +$32.2M 0.49% 70
2019
Q3 		$32.9M Buy
221,445
+33,468
+18% +$5.08M 0.26% 118
2019
Q2 		$28M Sell
187,977
-7,970
-4% -$1.09M 0.21% 145
2019
Q1 		$27.1M Sell
195,947
-9,275
-5% -$1.16M 0.21% 148
2018
Q4 		$22M Sell
205,222
-27,915
-12% -$3.11M 0.19% 147
2018
Q3 		$29M Sell
233,137
-372,250
-61% -$41.3M 0.2% 155
2018
Q2 		$59.1M Sell
605,387
-47,571
-7% -$4.52M 0.44% 77
2018
Q1 		$57.4M Buy
652,958
+164,490
+34% +$14.3M 0.44% 82
2017
Q4 		$41.4M Buy
488,468
+262,489
+116% +$22.8M 0.32% 118
2017
Q3 		$19.6M Sell
225,979
-6,105
-3% -$540K 0.15% 190
2017
Q2 		$21.2M Sell
232,084
-170,836
-42% -$15.7M 0.18% 164
2017
Q1 		$37.6M Sell
402,920
-136,793
-25% -$11.3M 0.32% 114
2016
Q4 		$36.4M Sell
539,713
-35,740
-6% -$2.2M 0.32% 110
2016
Q3 		$34.2M Sell
575,453
-250,011
-30% -$14.1M 0.28% 123
2016
Q2 		$43.3M Sell
825,464
-3,440
-0.4% -$162K 0.36% 95
2016
Q1 		$34.7M Buy
828,904
+292,881
+55% +$11M 0.26% 120
2015
Q4 		$22.3M Sell
536,023
-111,494
-17% -$4.56M 0.15% 174
2015
Q3 		$25M Sell
647,517
-245,471
-27% -$10M 0.18% 159
2015
Q2 		$34.6M Sell
892,988
-401,964
-31% -$14.4M 0.21% 130
2015
Q1 		$42.7M Buy
1,294,952
+298,957
+30% +$8.59M 0.25% 123
2014
Q4 		$26.2M Sell
995,995
-11,745
-1% -$290K 0.15% 177
2014
Q3 		$21.4M Sell
1,007,740
-25,290
-2% -$577K 0.13% 190
2014
Q2 		$24.4M Sell
1,033,030
-347,313
-25% -$8.61M 0.15% 182
2014
Q1 		$37.7M Sell
1,380,343
-30,170
-2% -$860K 0.23% 139
2013
Q4 		$41.2M Sell
1,410,513
-70,845
-5% -$1.98M 0.24% 129
2013
Q3 		$39.5M Sell
1,481,358
-113,920
-7% -$2.81M 0.25% 130
2013
Q2 		$33.8M Buy
+1,595,278
New +$33.6M 0.23% 144

Other funds holding MASI

BlackRock
BlackRock New York $5.72T AUM 30.48% 1-Year Est. Return
PCM
Politan Capital Management New York $985M AUM 3.12% 1-Year Est. Return
PCM
Pentwater Capital Management Naples, Florida $19.3B AUM 58.13% 1-Year Est. Return
Barclays
Barclays London, United Kingdom $416B AUM 33.63% 1-Year Est. Return
HI
HBK Investments Dallas, Texas $9.85B AUM 55.6% 1-Year Est. Return
Massachusetts Financial Services
Massachusetts Financial Services Boston, Massachusetts $298B AUM 21.96% 1-Year Est. Return
VCM
Vanguard Capital Management Malvern, Pennsylvania $4.04T AUM
VPM
Vanguard Portfolio Management Malvern, Pennsylvania $1.91T AUM
Fidelity Investments
Fidelity Investments Boston, Massachusetts $1.9T AUM 41.92% 1-Year Est. Return
State Street
State Street Boston, Massachusetts $2.9T AUM 29.55% 1-Year Est. Return

Westfield Capital Management's MASI Position: Q1 2026 in Review

Westfield Capital Management reduced its Masimo (MASI) stake by 78% in Q1 2026, selling an estimated $185M and leaving 341,229 shares worth $60.7M. The position accounts for 0.25% of the portfolio, ranked #123.

Westfield Capital Management first reported a position in MASI in Q2 2013 and has held it in 44 quarters since. The position peaked at $209M in Q3 2025. 445 funds tracked by Wall St. Rank hold MASI as of Q1 2026.

  • Westfield Capital Management held 341,229 shares of Masimo worth $60.7M as of Q1 2026.
  • Westfield Capital Management sold 1,180,820 Masimo shares in Q1 2026, an estimated $185M.
  • Masimo made up 0.25% of Westfield Capital Management's portfolio in Q1 2026, its #123 holding.
  • Westfield Capital Management first reported a position in Masimo in Q2 2013 and has held it in 44 quarters since.
  • Westfield Capital Management's Masimo position peaked at $209M in Q3 2025.
  • 445 funds tracked by Wall St. Rank held Masimo as of Q1 2026.

Based on Westfield Capital Management's 13F filing for Q1 2026, filed 11 May 2026.