There is a long list of 344 institutional holders of MASI within the last two holding periods in our database of 13F filers, so we've sorted through to present to you just the top 50 institutional holders of MASI by largest to smallest position reported in the institutional investor's latest 13F filing. In the institutional-holders-of-MASI table below, the initial column indicates the name of each top institutional holder of MASI, with a link to that fund's top holdings. The next columns indicate the amount of MASI stock held by each of the institutional holders of MASI, followed by the MASI position size held by the institution, and finally the date of the quarterly 13F filing period the holdings data represents for that institution.

Holder	Amount	Position Size ($ in 1000's)	As of
FMR LLC	6,927,572	$811,981	12/31/2023
MASI	6,927,572	$811,981	12/31/2023
BlackRock Inc.	5,659,131	$663,307	12/31/2023
MASI	5,659,131	$663,307	12/31/2023
Vanguard Group Inc.	4,781,343	$560,421	12/31/2023
MASI	4,781,343	$560,421	12/31/2023
Politan Capital Management LP	4,713,518	$552,471	12/31/2023
MASI	4,713,518	$552,471	12/31/2023
Capital Research Global Investors	2,269,189	$265,972	12/31/2023
MASI	2,269,189	$265,972	12/31/2023
Massachusetts Financial Services Co. MA	1,607,310	$188,393	12/31/2023
MASI	1,607,310	$188,393	12/31/2023
RTW Investments LP	1,462,400	$171,408	12/31/2023
MASI	1,462,400	$171,408	12/31/2023
State Street Corp	1,357,402	$159,101	12/31/2023
MASI	1,357,402	$159,101	12/31/2023
Farallon Capital Management LLC	1,311,649	$153,738	12/31/2023
MASI	1,311,649	$153,738	12/31/2023
T. Rowe Price Investment Management Inc.	1,161,907	$136,188	12/31/2023
MASI	1,161,907	$136,188	12/31/2023
Thrivent Financial for Lutherans	1,063,381	$124,638	12/31/2023
MASI	1,063,381	$124,638	12/31/2023
Citadel Advisors LLC		$107,843	12/31/2023
MASI	764,079	$89,558	12/31/2023
Call	231,100	$27,087	12/31/2023
Put	75,100	$8,802	12/31/2023
Schroder Investment Management Group	877,539	$102,856	12/31/2023
MASI	877,539	$102,856	12/31/2023
Liontrust Investment Partners LLP	852,393	$99,909	12/31/2023
MASI	852,393	$99,909	12/31/2023
Westfield Capital Management Co. LP	818,476	$95,934	12/31/2023
MASI	818,476	$95,934	12/31/2023
Jackson Square Partners LLC	762,329	$89,353	12/31/2023
MASI	762,329	$89,353	12/31/2023
Geode Capital Management LLC	723,936	$84,866	12/31/2023
MASI	723,936	$84,866	12/31/2023
Alyeska Investment Group L.P.	534,715	$62,674	12/31/2023
MASI	534,715	$62,674	12/31/2023
Point72 Asset Management L.P.	516,356	$60,522	12/31/2023
MASI	516,356	$60,522	12/31/2023
Sumitomo Mitsui Trust Holdings Inc.	391,889	$57,549	03/31/2024
MASI	391,889	$57,549	03/31/2024
Bank of New York Mellon Corp	390,925	$57,407	03/31/2024
MASI	390,925	$57,407	03/31/2024
Morgan Stanley	458,024	$53,685	12/31/2023
MASI	458,024	$53,685	12/31/2023
MIG Capital LLC	447,279	$52,426	12/31/2023
MASI	447,279	$52,426	12/31/2023
ArrowMark Colorado Holdings LLC	425,713	$49,898	12/31/2023
MASI	425,713	$49,898	12/31/2023
Price T Rowe Associates Inc. MD	410,508	$48,117	12/31/2023
MASI	410,508	$48,117	12/31/2023
Balyasny Asset Management LLC		$48,048	12/31/2023
MASI	302,535	$35,460	12/31/2023
Call	107,400	$12,588	12/31/2023
Ensemble Capital Management LLC	372,178	$43,623	12/31/2023
MASI	372,178	$43,623	12/31/2023
Charles Schwab Investment Management Inc.	368,041	$43,138	12/31/2023
MASI	368,041	$43,138	12/31/2023
JPMorgan Chase & Co.	355,199	$41,633	12/31/2023
MASI	355,199	$41,633	12/31/2023
Northern Trust Corp	347,353	$40,713	12/31/2023
MASI	347,353	$40,713	12/31/2023
Hawk Ridge Capital Management LP	342,528	$40,148	12/31/2023
MASI	342,528	$40,148	12/31/2023
Dimensional Fund Advisors LP	301,488	$35,339	12/31/2023
MASI	301,488	$35,339	12/31/2023
Woodline Partners LP	282,275	$33,085	12/31/2023
MASI	282,275	$33,085	12/31/2023
Raymond James & Associates	181,611	$26,670	03/31/2024
MASI	181,611	$26,670	03/31/2024
FIL Ltd	216,474	$25,373	12/31/2023
MASI	216,474	$25,373	12/31/2023
Millennium Management LLC		$25,371	12/31/2023
MASI	196,460	$23,027	12/31/2023
Call	20,000	$2,344	12/31/2023
HBK Investments L P		$23,442	12/31/2023
Call	200,000	$23,442	12/31/2023
Legal & General Group Plc	191,198	$22,410	12/31/2023
MASI	191,198	$22,410	12/31/2023
Marshall Wace LLP	189,053	$22,159	12/31/2023
MASI	189,053	$22,159	12/31/2023
Sei Investments Co.	180,628	$21,171	12/31/2023
MASI	180,628	$21,171	12/31/2023
Goldman Sachs Group Inc.	175,510	$20,572	12/31/2023
MASI	175,510	$20,572	12/31/2023
Federated Hermes Inc.	168,651	$19,768	12/31/2023
MASI	168,651	$19,768	12/31/2023
Principal Financial Group Inc.	164,627	$19,296	12/31/2023
MASI	164,627	$19,296	12/31/2023
Nine Ten Capital Management LLC	163,925	$19,214	12/31/2023
MASI	163,925	$19,214	12/31/2023
Jane Street Group LLC		$17,582	12/31/2023
MASI	86,506	$10,139	12/31/2023
Call	71,700	$8,404	12/31/2023
Put	8,200	$961	12/31/2023
Retirement Systems of Alabama	144,792	$16,971	12/31/2023
MASI	144,792	$16,971	12/31/2023
Rhumbline Advisers	137,951	$16,169	12/31/2023
MASI	137,951	$16,169	12/31/2023
BNP PARIBAS ASSET MANAGEMENT Holding S.A.	137,294	$16,092	12/31/2023
MASI	137,294	$16,092	12/31/2023
Rockefeller Capital Management L.P.	128,091	$15,014	12/31/2023
MASI	128,091	$15,014	12/31/2023
Wells Fargo & Company MN	116,712	$13,680	12/31/2023
MASI	116,712	$13,680	12/31/2023