Warren Buffett has made a remarkable $10.5 billion sale of Berkshire Hathaway’s stake in Bank of America in just a few months. Recent filings with the U.S. Securities and Exchange Commission reveal that the firm sold an additional 8.54 million shares in September and October, totaling $337.86 million. This move follows Berkshire’s complete exit from positions in JPMorgan Chase and Wells Fargo in recent years, making it the 15th round of relentless sales of BofA shares.

As a result of these sales, Berkshire’s overall stake in the bank has fallen below 10%, according to Fortune. This is a significant threshold because it means that Berkshire will only have to report its BofA trades every quarter, rather than every few days. Therefore, investors will not know if Berkshire continues to sell until mid-November.

Buffett has not publicly disclosed why he specifically reduced the firm’s exposure to Bank of America. However, he did express concerns about the banking sector as a whole last year. He stated, “You don’t know what has happened to the stickiness of deposits at all. It got changed by 2008. It’s gotten changed by this. And that changes everything. We’re very cautious in a situation like that about ownership of banks.”

Despite the sell-off, Berkshire remains the largest shareholder of Bank of America, with its position in the financial giant now valued at approximately $31 billion.