What major increases and decreases did top U.S. stock investment firms make in Q4?

According to SEC 13F securities reports:
1. Berkshire Hathaway (Berkshire Hathaway) — Warren Buffett
Major new positions: Purchased approximately $908 million worth of Liberty/Viacom affiliated stocks (Liberty/Viacom) and The New York Times (NYT).
Major increases: Continued to add to positions in Chubb (Chubb), C(, Chevron )C(, and Domino’s Pizza )DPZ(.
Major reductions: Further cut holdings in Apple )Apple( (reducing about 4.3%), and about 8.9% in Bank of America )BAC(. Also significantly reduced Aon PLC )AON( and liquidated some Amazon )AMZN( positions.
2. Bridgewater Associates )Bridgewater Associates( — Ray Dalio
Major new positions: Opened 191 new stocks in a single quarter, including Robinhood )HOOD(, Humana )HUM(, and Zebra Technologies )ZBRA(.
Major increases: Demonstrated high confidence in AI sector, buying about 1.35 million shares of Nvidia )NVDA(, bringing total holdings to $720 million. Also significantly increased holdings in Oracle )ORCL( (up 361%) and Micron Technology )MU(.
Major reductions: Sold off Microsoft )MSFT(, Amazon )AMZN(, and Visa )V(, and sharply cut the iShares Core MSCI Emerging Markets ETF )IEMG(.
3. Soros Fund Management )Soros Fund Management( — George Soros
Major new positions: Established new gold-related holdings such as New Gold )NGD(, and bought DigitalBridge )DBRG( and Confluent )CFLT(.
Major increases: Embraced core AI assets, adding 161,000 shares of Microsoft )MSFT( and 118,000 shares of Nvidia )NVDA(, while also increasing Uber )UBER( and Atlassian )TEAM(.
Major reductions: Aggressively sold Snowflake )SNOW( (selling 65% of the position) and liquidated some KeyCorp and certain cryptocurrency mining stocks. Also hedged energy and semiconductor industry risks with put options.
4. Pershing Square )Pershing Square( — Bill Ackman
Major new positions: Established a large position in Meta Platforms )META( for the first time (2.67 million shares).
Major increases: Significantly increased holdings in Amazon )AMZN( (+65%) and Brookfield Corp )BN( (+50%).
Major reductions: Reduced Alphabet )GOOGL( by about 86% of Class A shares, and slightly decreased Uber and Restaurant Brands )QSR(.
5. H&H International Investment — Duan Yongping
Significantly increased positions in semiconductor and AI computing fields:
Nvidia )NVDA(: Shares surged by 1,110.62% (accounting for 7.72% of holdings).
Berkshire Hathaway )BRK.B(: Increased by about 38.24% (nearly 2 million shares), serving as a defensive allocation and remaining the second-largest holding.
TSMC )TSM(: Shares increased by 370.95%.
Microsoft )MSFT(: Shares grew by 207.66%.
Pinduoduo )PDD(: Increased by about 34.55% (2.96 million shares).
New positions: First-time purchases of CoreWeave )CRWV( (AI cloud computing), Credo Technology )CRDO( (data center interconnect), and Tempus AI )TEM$NVDA (medical AI).
Reduced holdings in APPL, ASML, BABA;
Summary:
1. Most top investment firms continue to bet on AI;
2. Our positions are built at lower average costs than institutional averages;
3. Pre-market at 641, bought some $META