Berkshire Hathaway reported a 3.79% decline in second-quarter earnings as CEO Warren Buffett's company warned about President Donald Trump's tariffs on imported goods.

Berkshire Hathaway, the conglomerate run by legendary investor and soon-to-be-departing CEO Warren Buffett, on Saturday reported that it had recorded a nearly $5 billion second-quarter write-down of Kraft Heinz shares.

Berkshire said the 12 per cent quarterly decline in insurance underwriting profit stemmed primarily from reinsurance businesses and some smaller insurance businesses. Geico, its best-known insurance business, saw pre-tax underwriting profit rise 2 per cent, as a 5 per cent increase in premiums offset a smaller rise in accident losses.