The market is off to a tough start in 2022 with just days remaining in the first quarter of the year. The S&P 500 Index has fallen roughly 6.5% so far this year, the Dow Jones Industrial Average is down roughly 5.6%, and the Nasdaq Composite is well into correction territory and down roughly 11.7%. One stock that has performed very well this year is Warren Buffett's Berkshire Hathaway (BRK.A -0.28%) (BRK.B -0.68%), with class A and B shares up roughly 16% and 16.8%, respectively. A large segment within Berkshire is the conglomerate's equities portfolio, which is currently valued at around $349 billion. Buffett is widely considered one of the greatest investors of all time, so it's always a good idea to see what the Oracle of Omaha is up to. Here are the three best-performing stocks in Buffett and Berkshire's portfolio so far this year.

1. Occidental Petroleum

Buffett and Berkshire first received preferred shares in the American energy company Occidental Petroleum (OXY -0.09%) in 2019 to help assist the company with its purchase of Anadarko Petroleum. That deal was in effect a loan. Buffett gave Occidental $10 billion and in return collects a nice annual dividend yield of 8%. As part of the deal, Berkshire and Buffett also received 83.9 million common shares through warrants, which have a strike price of $59.62.

Earlier this year, Berkshire began buying common shares of Occidental and has accumulated roughly 136.4 million of common shares overall. Berkshire purchased the majority of these shares in March for prices between $47.62 and $56.28, according to Securities and Exchange Commission filings. In total, Buffett owns about 14.6% of Occidental's total outstanding shares. With the stock currently trading at $59.23, Buffett's position is currently worth close to $8.1 billion.

Occidental, which is one of the largest energy producers in the U.S., is currently up nearly 93% YTD. This is in part due to rising fuel prices sparked by Russia's invasion of Ukraine. Occidental makes most of its revenue from oil and gas, and crude oil prices have surged as high as $130 amid the U.S. ban imports of Russian oil, one of the world's largest energy producers.

Warren Buffett.

Image source: Motley Fool.

2. Chevron

Unsurprisingly, another major U.S. oil producer in Buffett's portfolio, Chevron (CVX 0.44%), has also taken off and currently trades about 39% higher so far in 2022. At roughly $169 per share and with a market cap of almost $330 billion, Chevron is trading near all-time highs.

Buffett has had an interesting couple of years with Chevron. Berkshire first acquired a more than $4 billion stake in the company in the fourth quarter of 2020. Then just three months later, Berkshire almost chopped that stake in half. But in the third quarter of 2021, Berkshire reversed course again and upped its stake in the California-based company by roughly 24%. And in the final quarter of 2021, Buffett and Berkshire bought more Chevron. At the end of 2021, the Oracle of Omaha owned about 38.2 million shares of Chevron, which are currently valued at roughly $6.36 billion.

Although it's at all-time highs, Chevron looks to be benefiting from more than just Russia's invasion and the rising price of oil. The company has now raised its annual dividend for 35 consecutive years, recently increased its share repurchase plans, and raised its operating cash flow projections through the year 2026.

3. Kroger Co

The third-largest gainer in Buffett and Berkshire's portfolio this year is not primarily an energy or oil company -- it's the supermarket and retail chain Kroger (KR 0.94%), which sells groceries, gas, and other retail products. Buffett and Berkshire first purchased Kroger in the fourth quarter of 2019, buying roughly $18.9 million shares, which at the time of the purchase were valued at more than $549 million. At the end of 2021, Berkshire has significantly upped that stake and now owns 61.4 million shares. At its current share price of $57.31, Buffett's stake in Kroger is worth roughly $3.5 billion.

Shares of Kroger are up about 25% this year, partly because the historic company is seen as an inflation hedge. Most major grocery stores like Kroger don't make huge margins but can expect to see them expand, as food and grocery prices have spiked over the past year. Notably, the pandemic has also led to more people cooking and eating at home. Many are also using the increasingly-popular online grocery deliveries.