Berkshire Hathaway Inc.’s cash pile soared to $381.7 billion in the third quarter, a fresh record, and operating earnings at Chief Executive Officer Warren Buffett’s conglomerate surged 34%.

That figure hit $13.5 billion, driven by an increase in insurance underwriting profit, in a period that was marked by an unusually low disaster activity, according to filings published Saturday.

Buffett offloaded $6.1 billion of shares during the period. In spite of that growing cash hoard, the firm’s net investment income declined 13% to $3.2 billion amid lower short-term interest rates.

The firm’s collection of primary insurance and reinsurance businesses both turned a pretax underwriting profit this quarter, after posting losses in the year-ago period.

But Berkshire auto insurer Geico’s pretax

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