You've probably heard of the 80-20 rule. It's also known as the Pareto principle. The idea is that roughly 80% of outcomes are generated by around 20% of causes. This 80-20 rule applies in a surprisingly large number of scenarios. As a case in point, look at where Warren Buffett and his team have invested Berkshire Hathaway's (BRK.A -0.34%) (BRK.B -0.01%) money. 

Berkshire has stakes in 47 companies. (There are actually 50 stocks, though, because some of the companies have multiple categories or series of shares.) The Pareto principle percentages don't apply exactly to Berkshire's investments, but they're really close. Eighty percent of Buffett's portfolio is invested in these seven stocks as 2023 begins.

1. Apple

Apple (AAPL 0.64%) ranks by far as the largest holding for Buffett, making up 36.8% of Berkshire's total portfolio (including shares owned by Berkshire's New England Asset Management subsidiary). The stock fell sharply in 2022. Don't be surprised if Buffett adds even more to his position in Apple with the tech giant trading at a discount.

2. Bank of America

Buffett's love of bank stocks has waned somewhat over the last year or so. However, he remains a fan of Bank of America (BAC 1.70%). The stock makes up 10.8% of Berkshire's portfolio (including shares owned by New England Asset Management). Although BofA's share price fell quite a bit in 2022, the big bank should benefit from higher interest rates in the new year.

3. Chevron

Chevron (CVX 0.57%) holds the No. 3 spot, comprising 9.6% of Berkshire's total portfolio. Buffett has bet heavily on the oil and gas giant -- and that bet has paid off nicely so far. Chevron's shares soared in 2022 and played a big role in helping Buffett beat the market.

4. Coca-Cola

Buffett has liked Coca-Cola (KO 0.15%) -- both the beverages and the stock -- for decades. The blue chip stock currently makes up 8.1% of Berkshire's total portfolio. Although Coca-Cola badly underperformed the S&P 500 over the last 10 years, it trounced the major index in 2022.

5. American Express

American Express (AXP 2.56%) stands out as another longtime favorite for Buffett. Out of Berkshire's total portfolio, 7% is invested in the financial services stock. Amex has been a big winner for Buffett over the long term. However, 2022 was a down year for the stock even though it outperformed the overall market.

6. Kraft Heinz

Berkshire owns a 26.6% stake in Kraft Heinz (KHC -0.21%). That's enough to make up 4.2% of the conglomerate's total portfolio. It's also enough for Kraft Heinz to be listed as a subsidiary company on Berkshire's website. And while Kraft Heinz stock has generally performed dismally over the last decade, it ranks among Buffett's winners in 2022.

7. Occidental Petroleum

Occidental Petroleum (OXY 0.58%) enjoyed a tremendous year in 2022. Its valuation more than doubled. That made it not only the best-performing stock of the year for Buffett but also the biggest winner in the S&P 500. The huge gains combined with aggressive buying throughout 2022 catapulted Occidental into the No. 7 spot for Buffett, making up 3.9% of Berkshire's total portfolio. 

Applying the 80-20 rule to these top Buffett stocks

Will the Pareto principle apply to these top Buffett stocks in 2023, with roughly 20% of them generating 80% of total returns for the year? We'll have to wait and see. However, I wouldn't be surprised if one or two of these stocks deliver outsized returns in 2023.

If I had to pick the most likely to succeed, Occidental would be at the top of the list. Of all the stocks Buffett bought in 2022, the oil stock appears to be among the best bets for 2023, in my view. 

I expect that oil prices will remain high, helping both Occidental and Chevron. It also seems likely that Buffett will continue to scoop up additional shares of Occidental. Berkshire secured approval in August 2022 to buy up to 50% of the oil and gas producer. Maybe the company won't acquire that big of a stake. Like the 80-20 rule, the actual percentage might not be exact, but it could be close.