William John Sempolinski
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William John Sempolinski’s Rocket Lab Corp RKLB Stock Holding History

William John Sempolinski’s Portfolio RKLB Stock Details RKLB Fund Activity
Bought
Maintained
Sold
Quarter Market Value Status Shares Change in
Stake 		Trade Value Portfolio Weight Portfolio Position
2026
Q3 		$2.3M Buy
33,075
+7,275
+28% +$524K 0.89% 26
2026
Q2 		$2.62M Sell
25,800
-750
-3% -$74.7K 1.06% 22
2026
Q1 		$1.71M Sell
26,550
-3,550
-12% -$268K 0.86% 27
2025
Q4 		$2.1M Buy
+30,100
New +$1.73M 1.03% 21

Other funds holding RKLB

BlackRock
BlackRock New York $6.79T AUM 37.06% 1-Year Est. Return
Vanguard Portfolio Management
Vanguard Portfolio Management Malvern, Pennsylvania $2.21T AUM
Vanguard Capital Management
Vanguard Capital Management Malvern, Pennsylvania $4.76T AUM
Invesco
Invesco Atlanta, Georgia $1.27T AUM 50.62% 1-Year Est. Return
State Street
State Street Boston, Massachusetts $3.44T AUM 36.12% 1-Year Est. Return
Geode Capital Management
Geode Capital Management Boston, Massachusetts $1.92T AUM 36.1% 1-Year Est. Return
Baillie Gifford & Co
Baillie Gifford & Co Edinburgh, United Kingdom $106B AUM 2.29% 1-Year Est. Return
JP Morgan Chase
JP Morgan Chase New York $1.84T AUM 33.86% 1-Year Est. Return
Capital World Investors
Capital World Investors Los Angeles, California $824B AUM 37.44% 1-Year Est. Return
Morgan Stanley
Morgan Stanley New York $1.96T AUM 27.49% 1-Year Est. Return

William John Sempolinski's RKLB Position: Q3 2026 in Review

William John Sempolinski increased its Rocket Lab Corp (RKLB) stake by 28% in Q3 2026, buying an estimated $524K and bringing the position to 33,075 shares worth $2.3M. The position accounts for 0.89% of the portfolio, ranked #26.

William John Sempolinski first reported a position in RKLB in Q4 2025 and has held it in 4 quarters since. The position peaked at $2.62M in Q2 2026. 897 funds tracked by Wall St. Rank hold RKLB as of Q3 2026.

  • William John Sempolinski held 33,075 shares of Rocket Lab Corp worth $2.3M as of Q3 2026.
  • William John Sempolinski bought 7,275 Rocket Lab Corp shares in Q3 2026, an estimated $524K.
  • Rocket Lab Corp made up 0.89% of William John Sempolinski's portfolio in Q3 2026, its #26 holding.
  • William John Sempolinski first reported a position in Rocket Lab Corp in Q4 2025 and has held it in 4 quarters since.
  • William John Sempolinski's Rocket Lab Corp position peaked at $2.62M in Q2 2026.
  • 897 funds tracked by Wall St. Rank held Rocket Lab Corp as of Q3 2026.

Based on William John Sempolinski's 13F filing for Q3 2026, filed 20 Oct 2026.