Top investment institutions have released the latest 13F filings. Buffett's Berkshire reveals UnitedHealth Stake, Trims Apple; BlackRock takes heavy positions on the “Big Seven”.

Berkshire Hathaway 13F Filing Reveals Warren Buffett's Secret Stock

Warren Buffett’s Berkshire Hathaway revealed a position in embattled healthcare giant UnitedHealth Group and reported smaller stakes in longtime holdings Apple and Bank of America, according to a regulatory filing Thursday.

Berkshire (BRK.A, BRK.B) at the end of the second quarter held 5 million shares of UnitedHealth Group (UNH) valued at about $1.6 billion.

The company has likely been accumulating shares since the fourth quarter of last year, when it first asked regulators to let it build a position in secret to avoid a price spike. Shares of UnitedHealth Group jumped more than 10% in extended trading Thursday.

Berkshire also opened smaller new positions in security products provider Allegion (ALLE), homebuilder D.R. Horton (DHI), Lamar Advertising (LAMR), and steelmaker Nucor (NUE), all of which saw their stocks rise after hours.

T-Mobile (TMUS) was Berkshire’s sole exit. The conglomerate sold the entirety of its $1 billion stake in the telecommunications giant. It also offloaded nearly half of its Charter Communications (CHTR) holdings.

Berkshire made smaller cuts to two of its largest holdings, selling 20 million of its 300 million Apple (AAPL) shares and 26 million of its 630 million Bank of America (BAC) shares. Buffett began paring Berkshire’s stakes in both last year.

Buffett scooped up 3 million shares of Chevron (CVX), another of his biggest holdings, and left stakes in longtime investments Coca-Cola (KO) and American Express (AXP) untouched.

Berkshire slashed its exposure to banks in the first quarter, exiting its position in Citigroup (C) and trimming its holdings of Bank of America and Capital One (COF). On the flip side, the firm added to some of its food and beverage holdings, including alcohol maker Constellation Brands (STZ) and Domino’s Pizza (DPZ).

In the second quarter, the firm seemed to favor homebuilders. On top of entering D.R. Horton, Berkshire bought about 7 million shares of competitor Lennar (LEN), upping its stake from just 150,000 shares.

Berkshire shares have shed about 11% of their value since Buffett announced in early May that he would step down as CEO at the end of 2025. Still, the stock is up almost 6% since the start of the year.

Renaissance Technologies top Q2 moves include AMD, Walmart exits, new UNH buy, others

Renaissance Technologies took new stakes in UnitedHealth Group (NYSE:UNH), with 1.35M shares, Snowflake (SNOW), with 717K shares, and Fiserv (FI), with 733K shares, during the second quarter, according to the hedge fund's latest 13F filing published on Wednesday.

Meanwhile, the Jim Simons-founded firm exited its holdings in Advanced Micro Devices (NASDAQ:AMD), Walmart (NYSE:WMT) ServiceNow (NOW) and Starbucks (SBUX) during the three months ended June 30, 2025.

It boosted its positions in Nvidia (NVDA), to 7.42M shares in Q2 from 1.08M in Q1, Netflix (NFLX), to 539K from 408, and Apple (AAPL), to 2.29M from 4.38K.

Decreased stakes include Broadcom (AVGO), to 764 shares in Q2 from 2.43M in Q1, and United Airlines (UAL), to 15.5K from 2.18M, the filing showed.

BlackRock Favors the "Big Seven" U.S. Stocks

In the second quarter, the asset management giant BlackRock established positions in 265 stocks, increased holdings in 2,144 stocks, reduced holdings in 2,649 stocks, and liquidated holdings in 238 stocks.

The top ten holdings accounted for 28.07% of the total market value.

As of June 30, large tech companies still constituted the majority of the top ten holdings.

NVIDIA ranked first, with a total of 1.91 billion shares, representing 5.47% of the investment portfolio, an increase of 0.42% from the first quarter.

In terms of specific changes, in the second quarter, BlackRock also increased its holdings in Apple and Amazon, but sold 1.7079 million shares of Microsoft, along with minor reductions in META.

In the second quarter, BlackRock established positions in "stablecoin top stock" Circle and social investment platform eToro Group.

The top five sales involved Procter & Gamble, Visa, Chevron, Merck, and Thermo Fisher Scientific.