Billionaire investor Warren Buffett’s Berkshire Hathaway made major changes to its stock portfolio this week, leading to a decline in shares of Taiwan Semiconductor Manufacturing Co. (TSMC).

On Tuesday, Berkshire Hathaway announced it was reducing its stake in TSMC by 86%, selling more than $5 billion worth of shares. This move caused TSMC shares to drop by nearly 2.5%.

Berkshire Hathaway also reduced its stake in several banks, including JPMorgan Chase, Bank of America, and Wells Fargo.

At the same time, the firm increased its stake in Apple by more than 1%. Berkshire Hathaway now owns more than 250 million shares of Apple, worth over $50 billion.

The moves by Warren Buffett’s firm come as the stock market continues to be volatile due to the ongoing COVID-19 pandemic. Investors are closely watching Berkshire Hathaway’s portfolio for any further changes.