Warren Buffett's Berkshire Hathaway cuts its stake in GM by 45%

Warren Buffett's investment company Berkshire Hathaway said it nearly halved its stake in General Motors in the second quarter.

The firm sold 45 percent of its stake in GM, reducing its shares from about 40 million to about 22 million, according to a quarterly filing on Monday with the U.S. Securities and Exchange Commission.

David Whiston, a U.S. auto equity analyst at Morningstar Research Services, told Automotive News that Berkshire Hathaway's motivation for selling is unclear.

"It could be a variety of reasons from UAW risk, to being tired of waiting for the stock to rally, to macro risk owning a cyclical name, to just having a better idea and wanting to reallocate capital," he said.

GM declined to comment on Berkshire Hathaway's reduction in its stake in the quarter ending June 30. Berkshire Hathaway also declined to comment. In the same filing, Berkshire Hathaway revealed new investments in several homebuilder companies.

Investor concern over a possible strike amid UAW negotiations with the Detroit 3 is on the rise. GM shares, for example, saw a 5.8 percent drop on Thursday — the company's biggest daily plunge in nearly eight months.

Buffett has long been loyal to the Detroit 3 and was known for driving a Cadillac. In 2012, Berkshire acquired 10 million shares in GM, but the firm's stake has grown and shrunk over the past decade amid recalls and other developments.

Berkshire Hathaway also sold off millions of its Hong Kong Stock Exchange shares in Chinese EV maker BYD this year.

GM shares slipped 2.26 percent to $33.30  when the market closed Tuesday.