The stock market rout that occurred at the end of last year hurt Berkshire Hathaway’s 2018 profits, at least on paper.

The conglomerate controlled by Warren E. Buffett suffered losses of $25.4 billion in the fourth quarter, according to Berkshire’s annual report that was released on Saturday. The company owns $173 billion of stocks and the market’s swoon in the fourth quarter helped cause losses of $22.7 billion on those securities. Berkshire also recorded a $3 billion noncash loss related to its large stake in Kraft Heinz, the struggling food company. (Stocks, of course, have recovered this year, and Berkshire’s losses may now be smaller.)

In his annual letter to Berkshire’s shareholders that accompanied its results, Mr. Buffett urged investors to focus on the performance of Berkshire Hathaway’s broad array of companies, which includes insurers, energy firms, railways and manufacturers. These firms did well last year, posting a 36 percent increase in earnings.

Before 2018, Berkshire did not include the performance of its stock holdings in its income statement, unless it sold the shares. But a new accounting rule requires that the company include the paper gains and losses. That is something Mr. Buffett has criticized, saying the rule would cause “wild and capricious” swings in Berkshire’s bottom line. In this year’s letter, he wrote, “Indeed, in the fourth quarter, a period of high volatility in stock prices, we experienced several days with a ‘profit’ or ‘loss’ of more than $4 billion.”