(Reuters) – Berkshire Hathaway unloaded more Bank of America stock this week, boosting sales since mid-July to nearly $10 billion as Warren Buffett simplifies part of his conglomerate’s vast portfolio.

In a regulatory filing on Wednesday night, Berkshire said it sold 8.55 million Bank of America shares this week for about $337.9 million. It has sold about 238.7 million shares, or about 23% of its holdings, since mid-July.

Berkshire still owns about 10.2% of the second-largest U.S. bank, or a slightly higher percentage if Bank of America has yet to disclose recent stock buybacks.

It must continue reporting sales until and including thesale that drives its stake below 10%. Thereafter, investors must likely wait for Berkshire’squarterly financial reports or quarterly stock holdingsdisclosures to learn if the Omaha, Nebraska-based company soldmore. The U.S. Securities and Exchange Commission requires shareholders that own more than 10% of a company to disclose stock purchases and sales within two business days.

Berkshire’s selling reduces to a more manageable size whathad been its second-largest stock holding, which originated in a$5 billion investment in 2011.

The company also more than halved its largest stock holding,Apple, in the year’s first half.

Buffett, 94, tied up another loose end this week when the company agreed to buy the 8% it did not already own of its energy and utility business Berkshire Hathaway Energy from the estate of billionaire philanthropist Walter Scott.

Berkshire ended June with $276.9 billion of cash. It will spend $2.37 billion of cash in the Berkshire Hathaway Energy transaction.

Buffett has run Berkshire since 1965. His conglomerate’s dozens of businesses include the BNSF railroad, Geico car insurance, and smaller operations such as Dairy Queen and See’s Candies.

(Reporting by Jonathan Stempel in New York; Editing by Nick Zieminski)