Warren Buffett and his holding company Berkshire Hathaway (NYSE:BRK.A) (NYSE:BRK.B) together are giants. Buffett, of course, became iconic in the investing world by picking huge winners such as Coca-Cola (NYSE:KO) and Bank of America (NYSE:BAC). Berkshire Hathaway became a leading conglomerate because of Buffett's investing and business-savvy ways. Buffett's track record could continue to further improve due to the potential for several of his top stocks to outperform.

Stocks that Warren Buffett recently bought

While Buffett opened new positions in several stocks in previous quarters, the legendary investor was much more selective in the first quarter of 2021. Only one new stock was added to Berkshire's portfolio: AON (NYSE:AON). Berkshire bought 4,096,146 shares in the professional services company for $942,564,000.

AON, which generates strong recurring cash flow, appears to be a great fit for Buffett. The company's offerings include customized insurance solutions, cybersecurity consulting services, health and benefits brokerage services, healthcare exchanges, reinsurance, retail brokerage services, and retirement solutions. These cash-rich businesses are what the Oracle of Omaha, as Buffett is often called, especially likes. 

Warren Buffett with people in the background

Image source: The Motley Fool.

Buffett in the first quarter of 2021 also directed Berkshire Hathaway to increase its existing stakes in these four companies:

Stock

Number of Shares Owned

Share Count Increase Over Q4 2020

Value of Total Stake

Kroger (NYSE:KR)

51,060,296

52.3%

$1.8 billion
Marsh & McLennan Companies (NYSE:MMC)

5,287,526

23.9%

$644 million
RH (NYSE:RH) 

1,756,448

1.4%

$1 billion
Verizon Communications (NYSE:VZ)

158,824,575

8.3%

$9.2 billion

Data source: Berkshire Hathaway 13F-HR filings. 

In Q1 of 2021, the legendary investor trimmed Berkshire Hathaway's positions in 11 stocks, including several pharmaceutical stocks:

Stock

Number of Shares Owned

Share Count Decrease From Q4 2020

Value of Total Stake

AbbVie (NYSE:ABBV)

22,868,178

10.4%

$2.5 billion
Axalta Coating Systems (NYSE:AXTA)

13,887,037

40.7%

$410.8 million
Bristol Myers Squibb (NYSE:BMY) 

31,032,227

6.9%

$2 billion
Chevron (NYSE:CVX) 

23,672,271

51.2%

$2.5 billion
General Motors (NYSE:GM)

67,000,000

7.6%

$3.8 billion
Liberty Global Class A (NASDAQ:LBTYA)

3,359,831

81.3%

$86.2 million
Merck (NYSE:MRK) 

17,882,388

37.7%

$1.4 billion
Sirius XM Holdings (NASDAQ:SIRI)

43,658,800

12.7%

$265.9 million
StoneCo (NASDAQ:STNE)

10,695,448

24.5%

$654.8 million
US Bancorp (NYSE:USB)

129,687,084

1.1%

$7.2 billion
Wells Fargo (NYSE:WFC)

675,054

98.7%

$26.4 million

Data source: Berkshire Hathaway 13F-HR filings. 

And, while Buffett's favorite holding time typically is "forever," he opted to completely close Berkshire Hathaway's positions in two stocks during the first quarter of 2021 -- Suncor Energy (NYSE:SU) and Synchrony Financial (NYSE:SYF).

Top stocks that Warren Buffett owns by size

In total, Berkshire Hathaway owns positions in more than 40 stocks. Here are Berkshire's top 10 stocks, ranked by the value of the holding:

Stock

Number of Shares Owned

Value of Stake

Apple (NASDAQ:AAPL) 907,559,761 $115.7 billion
Bank of America (NYSE:BAC) 1,032,852,006 $43 billion
American Express (NYSE:AXP) 151,610,700 $24.9 billion
Coca-Cola (NYSE:KO) 400,000,000 $22.2 billion
Kraft Heinz (NASDAQ:KHC) 325,634,818 $14 billion
Verizon Communications (NYSE:VZ) 158,824,575 $9.1 billion
U.S. Bancorp (NYSE:USB) 147,315,527 $8.7 billion
Moody's (NYSE:MCO) 24,669,778 $8.5 billion
BYD (OTC:BYDD.F) 225,000,000* $6.2 billion
DaVita (NYSE:DVA) 36,095,570 $4.4 billion

Data source: Berkshire Hathaway 13F-HR filing. Valuations current as of time of writing. *Number of shares owned as of Dec. 31, 2020, as reported in 2020 annual letter to shareholders.

There's a glaring gap between the values of the No. 1 and No. 2 stocks in the Berkshire Hathaway portfolio. In the top spot, Apple is such a massive holding that Buffett has referred to the technology giant as Berkshire Hathaway's "third-largest business" after its fully owned insurance and railroad businesses. Buffett has also described Apple as "probably the best business I know in the world."

As Berkshire Hathaway's second-largest position, Bank of America especially stands out because Buffett has reduced the positions of most of his bank stocks in recent quarters. The financial services leader continues to benefit from its investments in technology, including mobile apps.

Should you follow Buffett's moves?

While it can certainly be interesting to keep track of what Buffett and other billionaire investors are buying and selling, it's never a smart idea to jump into a stock just because someone else does -- even if that someone else is the Oracle of Omaha.

Having said that, looking at Berkshire Hathaway's stock portfolio can give you plenty of stock ideas to investigate further in order to determine what is suitable for your portfolio based on your own risk tolerance and investment objectives.