Every quarter, institutional managers who oversee over $100 million in U.S. equities must disclose their holdings to the SEC via Form 13F. That filing is a snapshot, not a trade blotter, so it does not reveal the exact date a position was opened, only that it existed at quarter’s end. Below is a ranked look at the largest brand-new positions initiated during the quarter ending 2026-03-31, based on real 13F disclosures. This is informational reporting only and not a recommendation to buy or sell any security.
1. 1832 Asset Management L.P. – SPDR S&P 500 ETF TR
The single largest new stake on this list dwarfs everything else in the group. 1832 Asset Management L.P. disclosed a brand-new position in the SPDR S&P 500 ETF TR valued at $27,639,450,000 as of the quarter ending 2026-03-31.
2. Capital International Investors – AstraZeneca PLC (AZN)
Capital International Investors opened a new stake in AstraZeneca PLC worth $6,724,768,674, making it the largest of several new AZN positions reported this quarter.
3. Capital World Investors – AstraZeneca PLC (AZN)
A related but distinct manager, Capital World Investors, also started a fresh AstraZeneca PLC position, this one valued at $5,520,442,676.
4. Capital Research Global Investors – Cisco Systems Inc
Capital Research Global Investors disclosed a new holding in Cisco Systems Inc worth $4,961,797,384 as of quarter-end.
5. PRIMECAP MANAGEMENT CO/CA/ – AstraZeneca PLC (AZN)
PRIMECAP MANAGEMENT CO/CA/ became the third distinct filer to open a new AstraZeneca PLC position this quarter, valued at $3,592,107,490.
6. Dodge & Cox – Sunbelt Rentals Holdings, Inc. (SUNB)
Dodge & Cox reported a new position in Sunbelt Rentals Holdings, Inc. worth $3,456,399,221.
7. PRUDENTIAL PLC – AstraZeneca PLC (AZN)
PRUDENTIAL PLC rounds out the AstraZeneca theme with a new stake valued at $3,237,325,549, the fourth manager on this list to initiate AZN exposure during the same quarter.
8. BROOKFIELD Corp /ON/ – Brookfield Business Corp (BBUC)
BROOKFIELD Corp /ON/ disclosed a new position in Brookfield Business Corp worth $2,819,054,455.
9. AMERICAN SECURITIES LLC – SOLV Energy Inc (MWH)
AMERICAN SECURITIES LLC opened a new stake in SOLV Energy Inc valued at $2,755,960,337.
10. Capital International Investors – Cloudflare Inc (NET)
Closing out the top 10, Capital International Investors also started a new position in Cloudflare Inc worth $2,247,610,066, a second new holding from the same filer on this list.
Readers who track superinvestor portfolio stats often ask whether hedge funds have to disclose their holdings at all. The answer is yes, but only through this quarterly 13F snapshot, which lags real-time activity and omits short positions and many derivatives. That lag is part of why these filings are best read as a historical record rather than a live signal of what large funds are doing right now.
Source: SEC Form 13F filings. This is informational reporting, not investment advice.