As of press time, BYD's shares traded in Hong Kong were down more than 11 percent and those traded in Shenzhen were down about 8 percent.
BYD said the market should not read too much into Warren Buffett's reduction of holdings, after the move has caused its shares to plunge.
"We only learned about it when we saw the disclosure and didn't know about it beforehand," local media outlet 21Jingji quoted a source in BYD's investor relations department as saying today.
There is a lot of speculation in the market about Buffett's move, and BYD does not know the specifics, the source said, adding that people need not over-interpret.
Recently, BYD has no major undisclosed matters, and the company's business is all normal, the person said.
On August 30, a Hong Kong Stock Exchange filing showed that Buffett's Berkshire Hathaway sold 1.33 million BYD H shares on August 24, the first time in 14 years to reduce its position in the company.
Berkshire sold those shares at an average trading price of HK$277.1 per share, meaning the move cashed in nearly HK$369 million for it.
Following the move, Berkshire's stake in BYD fell from 20.04 percent to 19.92 percent.
BYD Co (OTCMKTS: BYDDF)'s US-traded ADR fell 7.84 percent overnight as a result of the move. At press time, BYD's shares traded in Hong Kong were down more than 11 percent and those traded in Shenzhen were down about 8 percent.
On September 29, 2008, Berkshire Hathaway Energy, which is 91.1 percent owned by Berkshire, spent $230 million to buy 225 million shares of BYD at HK$8 each.
After that, there was no change in Berkshire's holding of BYD.
On July 11, the number of BYD H shares in Citi's seat reached 388.6 million shares, an increase of about 225 million shares from the previous week, which was seen at the time as a prelude to Warren Buffett's reduction of BYD's holdings.