RTW Investments’s Masimo MASI Stock Holding History

RTW Investments’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	–	Sell	-683,294	Closed	-$88.9M	–	94
2025 Q4	$88.9M	Hold	683,294	–	–	0.89%	31
2025 Q3	$101M	Hold	683,294	–	–	1.24%	23
2025 Q2	$115M	Hold	683,294	–	–	1.64%	22
2025 Q1	$114M	Hold	683,294	–	–	1.74%	20
2024 Q4	$113M	Sell	683,294 -779,106	-53%	-$123M	1.71%	24
2024 Q3	$195M	Hold	1,462,400	–	–	2.82%	15
2024 Q2	$184M	Hold	1,462,400	–	–	2.85%	13
2024 Q1	$215M	Hold	1,462,400	–	–	3.17%	10
2023 Q4	$171M	Sell	1,462,400 -39,093	-3%	-$3.64M	2.68%	14
2023 Q3	$132M	Hold	1,501,493	–	–	2.78%	13
2023 Q2	$247M	Hold	1,501,493	–	–	4.7%	7
2023 Q1	$277M	Hold	1,501,493	–	–	5.77%	6
2022 Q4	$222M	Buy	1,501,493 +61,500	+4%	+$8.46M	4.53%	7
2022 Q3	$203M	Buy	1,439,993 +89,000	+7%	+$13M	4.69%	6
2022 Q2	$177M	Buy	1,350,993 +223,400	+20%	+$29.9M	4.56%	5
2022 Q1	$164M	Buy	1,127,593 +277,622	+33%	+$53.3M	3.4%	6
2021 Q4	$249M	Buy	849,971 +17,431	+2%	+$4.96M	3.63%	5
2021 Q3	$225M	Buy	832,540 +6,330	+0.8%	+$1.72M	3.4%	6
2021 Q2	$200M	Buy	826,210 +231,254	+39%	+$52.8M	3.02%	10
2021 Q1	$137M	Buy	594,956 +125,540	+27%	+$31.5M	2.13%	13
2020 Q4	$126M	Buy	469,416 +19,026	+4%	+$4.74M	2.11%	14
2020 Q3	$106M	Buy	450,390 +61,614	+16%	+$13.8M	2.56%	12
2020 Q2	$88.6M	Buy	388,776 +5,861	+2%	+$1.29M	2.49%	11
2020 Q1	$67.8M	Buy	382,915 +728	+0.2%	+$125K	2.92%	10
2019 Q4	$60.4M	Buy	382,187 +11,032	+3%	+$1.66M	2.28%	15
2019 Q3	$55.2M	Sell	371,155 -1,103	-0.3%	-$168K	3.28%	9
2019 Q2	$55.4M	Buy	372,258 +8,689	+2%	+$1.19M	2.96%	11
2019 Q1	$50.3M	Buy	363,569 +21,348	+6%	+$2.68M	3.43%	7
2018 Q4	$36.7M	Buy	342,221 +31,760	+10%	+$3.54M	3.37%	10
2018 Q3	$38.7M	Buy	310,461 +60,918	+24%	+$6.76M	2.32%	11
2018 Q2	$24.4M	Buy	249,543 +17,543	+8%	+$1.67M	1.76%	13
2018 Q1	$20.4M	Buy	232,000 +111,100	+92%	+$9.68M	1.94%	17
2017 Q4	$10.3M	Hold	120,900	–	–	1.71%	18
2017 Q3	$10.5M	Buy	120,900 +20,000	+20%	+$1.77M	1.82%	19
2017 Q2	$9.2M	Buy	100,900 +20,000	+25%	+$1.84M	1.94%	16
2017 Q1	$7.54M	Hold	80,900	–	–	1.99%	14
2016 Q4	$5.45M	Buy	80,900 +55,000	+212%	+$3.38M	2.05%	14
2016 Q3	$1.54M	Hold	25,900	–	–	0.47%	27
2016 Q2	$1.36M	Hold	25,900	–	–	0.46%	26
2016 Q1	$1.08M	Hold	25,900	–	–	0.39%	26
2015 Q4	$1.07M	Hold	25,900	–	–	0.35%	23
2015 Q3	$999K	Buy	+25,900	New	+$1.06M	0.31%	32

Other funds holding MASI

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 London, United Kingdom $416B AUM 33.63% 1-Year Est. Return

HBK Investments Dallas, Texas $9.85B AUM 55.6% 1-Year Est. Return

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 Boston, Massachusetts $1.9T AUM 41.92% 1-Year Est. Return

State Street Boston, Massachusetts $2.9T AUM 29.55% 1-Year Est. Return

RTW Investments's MASI Position: Q1 2026 in Review

RTW Investments sold out of Masimo (MASI) in Q1 2026, closing a stake of 683,294 shares — an estimated $88.9M sold.

RTW Investments first reported a position in MASI in Q3 2015 and held it in 42 quarters. The position peaked at $277M in Q1 2023. 445 funds tracked by Wall St. Rank hold MASI as of Q1 2026.

RTW Investments reported no remaining Masimo position as of Q1 2026 after selling out during the quarter.
RTW Investments sold 683,294 Masimo shares in Q1 2026, an estimated $88.9M.
RTW Investments first reported a position in Masimo in Q3 2015 and held it in 42 quarters.
RTW Investments's Masimo position peaked at $277M in Q1 2023.
445 funds tracked by Wall St. Rank held Masimo as of Q1 2026.

Based on RTW Investments's 13F filing for Q1 2026, filed 15 May 2026.