They did a bit better than the index - the S&P 500 went up about 21% in 2021, Berkshire Hathaway went up 37%. 37% is a very respectable one-year return for any stock, particularly one that invests conservatively. Also not true that they simply wrap Apple, which went up 32% in 2021. They also beat Tesla, which went up 18%.
Where are you getting 21 vs 37%? I was just looking at their usual history table on pg3 https://www.berkshirehathaway.com/2021ar/2021ar.pdf#page=3 where for 2021, they list "29.6" vs "28.7". As a wrapper around Apple and other assets, and no mention of any incredible 2021 feats in the letter mostly waxing rhapsodic about their past, that sounds entirely plausible. (I also don't see any Berkshire year as high as 37% since 1998, 23 years ago.)
I went to Yahoo Finance and looked at the Jan 1 2022 vs Jan 1 2021 market prices, then plugged them into Google calculator to get a percentage gain. BRK-B = 313.2 / 227.87 = 37.88%, AAPL = 174.78 / 131.96 = 32.82%, S&P 500 = 4515 / 3714 = 21.56%. Not really sure how the table at the beginning of Berkshire's annual report is figured. Perhaps they're only marking the public equity portion of their portfolio to market and holding the private equity portion at the price they paid for it minus depreciation, as a sibling comment here suggested. This'll undercount things significantly since, as the annual report notes, they're the largest owner of private infrastructure in the U.S. Plus they bought many of those private assets in the 70s and 80s when price levels were a lot lower.
