Since the pandemic started in March of 2020, Legendary investor Warren Buffett and his company Berkshire Hathaway (BRK.A -0.30%) (BRK.B -0.26%) have done quite a bit of buying and selling in Berkshire's large equities portfolio. The pandemic has changed the world as we know it, which has changed the investment thesis for many stocks. The market's wild ride has also created scenarios in which stocks got overvalued and opportunities in which stocks were trading at a discount. Despite all of these changes, Berkshire does have some stocks that it hasn't sold a penny of and has maintained its exact position in over these last nearly 2.5 years. Here are three of them.

1. Amazon

Berkshire first began buying the e-commerce and tech giant Amazon (AMZN -1.65%) in May 2019 and then bought more later that year.

Berkshire timed this one pretty well because the pandemic would hit less than a year later, and shipping would become paramount across the world, as people were quarantined and avoided public places for months on end, especially early on in the pandemic. Amazon's stock has since performed well, and Buffett and Berkshire have held their position.

Earlier this year, Amazon announced a 20-for-1 stock split, the first split the company has done since 1999, and a $10 billion share repurchase program. Because of the split, the number of Amazon shares Berkshire owns looks different now than it did after the first quarter of 2020, but it's really the same amount.

2. American Express

Another stock Berkshire has maintained its large position in since the pandemic started is the credit card and payments company American Express (AXP -0.84%). Berkshire owned roughly 151.6 million shares following the first quarter of 2020 and owns that amount now. Berkshire's American Express position makes up roughly 6.6% of the company's entire portfolio. American Express' stock is also up from the levels it traded at prior to the pandemic, and it's a real testament to American Express that Buffett and Berkshire held onto the stock.

In 2020, Berkshire sold a lot of its bank holdings, concerned about the amount of exposure it had to the sector. The sell-off included other credit card companies, which can also experience more loan defaults during a recession than other types of loans, so they are more inherently risky than a traditional bank.

However, American Express serves a more affluent customer base, and Buffett has long thought the company has one of the best brands in the business, likely making it an easy decision to hold onto the stock during the pandemic.

3. Moody's

Berkshire has owned more than 24.6 million shares of Moody's (MCO -1.58%), the large credit rating agency and financial software company, since the first quarter of 2020, and it's another stock that trades higher now than it did at the beginning of 2020. Berkshire's position in Moody's makes up more than 2% of its portfolio. 

Berkshire has owned shares of Moody's for more than two decades now, but it hasn't all been smooth sailing. The conglomerate continued to hold shares as the stock plunged during the financial crisis.

Many suspected Moody's, along with other rating agencies, had been giving good investment grades to bad mortgage bonds so they could keep the business of major Wall Street banks. Buffett sold some of Moody's stock after the Great Recession when the stock was trading low but starting to make a comeback. This would ultimately turn into a big mistake for Buffett because Moody's stock has risen from below $30 in 2010 to more than $300 now. Still, Buffett has made good money on the investment overall.