Marshall Wace
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Marshall Wace’s iRhythm Holdings IRTC Stock Holding History

Marshall Wace’s Portfolio IRTC Stock Details IRTC Fund Activity
Bought
Maintained
Sold
Quarter Market Value Status Shares Change in
Stake 		Trade Value Portfolio Weight Portfolio Position
2026
Q1 		– Sell
-3,564
Closed -$632K – 3451
2025
Q4 		$632K Buy
3,564
+2,301
+182% +$408K ﹤0.01% 2146
2025
Q3 		$217K Buy
+1,263
New +$201K ﹤0.01% 2548
2024
Q4 		– Sell
-86,763
Closed -$6.44M – 2785
2024
Q3 		$6.44M Buy
+86,763
New +$6.91M 0.01% 906
2024
Q1 		– Sell
-209,537
Closed -$22.4M – 2621
2023
Q4 		$22.4M Buy
+209,537
New +$18.3M 0.04% 444
2022
Q3 		– Sell
-9,550
Closed -$1.03M – 3557
2022
Q2 		$1.03M Buy
+9,550
New +$1.27M ﹤0.01% 2424
2022
Q1 		– Sell
-31,733
Closed -$3.73M – 3657
2021
Q4 		$3.73M Buy
+31,733
New +$2.91M 0.01% 1596
2021
Q2 		– Sell
-30,306
Closed -$4.21M – 2843
2021
Q1 		$4.21M Buy
+30,306
New +$5.43M 0.02% 932
2020
Q3 		– Sell
-1,888
Closed -$219K – 1750
2020
Q2 		$219K Buy
+1,888
New +$208K ﹤0.01% 1396
2020
Q1 		– Sell
-3,958
Closed -$270K – 1848
2019
Q4 		$270K Buy
+3,958
New +$269K ﹤0.01% 1301
2019
Q1 		– Sell
-1,532
Closed -$107K – 1886
2018
Q4 		$107K Buy
+1,532
New +$116K ﹤0.01% 1356
2018
Q2 		– Sell
-7,200
Closed -$453K – 763
2018
Q1 		$453K Buy
+7,200
New +$446K 0.02% 388

Other funds holding IRTC

BlackRock
BlackRock New York $6.73T AUM 46.02% 1-Year Est. Return
Vanguard Portfolio Management
Vanguard Portfolio Management Malvern, Pennsylvania $2.22T AUM
RI
RTW Investments New York $11.7B AUM 174.13% 1-Year Est. Return
Millennium Management
Millennium Management New York $276B AUM 44.8% 1-Year Est. Return
Artisan Partners
Artisan Partners Milwaukee, Wisconsin $63.1B AUM 35.51% 1-Year Est. Return
Vanguard Capital Management
Vanguard Capital Management Malvern, Pennsylvania $4.68T AUM
Fidelity Investments
Fidelity Investments Boston, Massachusetts $2.3T AUM 54.33% 1-Year Est. Return
Holocene Advisors
Holocene Advisors New York $44.4B AUM 57.89% 1-Year Est. Return
UBS AM
UBS AM Chicago, Illinois $550B AUM 43.33% 1-Year Est. Return
Geode Capital Management
Geode Capital Management Boston, Massachusetts $1.88T AUM 44.46% 1-Year Est. Return

Marshall Wace's IRTC Position: Q1 2026 in Review

Marshall Wace sold out of iRhythm Holdings (IRTC) in Q1 2026, closing a stake of 3,564 shares — an estimated $632K sold.

Marshall Wace first reported a position in IRTC in Q1 2018 and held it in 11 quarters. The position peaked at $22.4M in Q4 2023. 305 funds tracked by Wall St. Rank hold IRTC as of Q1 2026.

  • Marshall Wace reported no remaining iRhythm Holdings position as of Q1 2026 after selling out during the quarter.
  • Marshall Wace sold 3,564 iRhythm Holdings shares in Q1 2026, an estimated $632K.
  • Marshall Wace first reported a position in iRhythm Holdings in Q1 2018 and held it in 11 quarters.
  • Marshall Wace's iRhythm Holdings position peaked at $22.4M in Q4 2023.
  • 305 funds tracked by Wall St. Rank held iRhythm Holdings as of Q1 2026.

Based on Marshall Wace's 13F filing for Q1 2026, filed 15 May 2026.