(Reuters) - Warren Buffett's Berkshire Hathaway has offloaded more shares in Bank of America, its latest filing showed on Tuesday, raking in about $9 billion since July.

The conglomerate said it sold around 21 million shares between Sept. 20 and Sept. 24 for around $863 million, following sales of about 45.6 million shares in multiple rounds earlier in the month.

Berkshire - which is still BofA's biggest shareholder - now owns a 10.5% stake in the U.S. banking major worth $32.13 billion, per LSEG data. If its holding falls below 10%, it will no longer be required to report stake sales regularly.

Earlier this month, BofA CEO Brian Moynihan praised Warren Buffett, saying he had been a "great investor" who "stabilized" the company.

"I don't know what exactly he is doing because, frankly, we can't ask," Moynihan told investors at a financial conference in New York.

Buffett began investing in the bank in 2011 when Berkshire bought $5 billion worth of preferred stock, signaling his confidence in Moynihan's ability to restore the lender to health following the 2008 financial crisis.

The billionaire, 94, swapped the preferred stock for common stock in 2017 after exercising warrants.

In April 2023, he told CNBC that he liked Moynihan "enormously" and did not want to sell the bank's stock at the time, despite exiting other banking sector investments.

BofA's shares were last down marginally in premarket trading. The stock has risen about 17% so far this year, while the S&P 500 Banks Index, which tracks large-cap banks, is up nearly 19%.

The benchmark S&P 500 has gained around 20% year-to-date.

(Reporting by Manya Saini in Bengaluru; Editing by Janane Venkatraman)