BYD’s share price slumped after the Chinese car giant raised HKD43.5 billion (USD5.6 billion) in a follow-on share sale in Hong Kong that was reportedly the largest in the global auto industry over the past decade.

BYD [SHE: 002594] closed 4.3 percent lower at CNY344.84 (USD47.81) a share in Shenzhen today. After earlier plunging by more than 8 percent, its Hong Kong-listed equity [HKG: 1211] ended down 6.8 percent at HKD339 (USD43.61).

BYD sold 129.8 million shares at HKD335.20 each, representing an 11.8 percent discount on the stock’s average closing price in Hong Kong for the last 10 days as of yesterday, it said in a stock exchange filing the same day. The names of the investors were not disclosed.

The Shenzhen-based company expects net proceeds of almost HKD43.4 billion from the sale after commissions and expenses, which will go on research and development, overseas business development, replenishing working capital and for general corporate purposes.

The new shares represent about 11.8 percent of the company’s almost 1.1 million Hong Kong-listed shares and about 4.46 percent of the total equity issued.

The sale was also the largest-ever so-called lightning placement in the global auto sector, according to The Paper. A lightning placement is a fast, high-tech process where a company's board authorizes the sale of as much as 20 percent of outstanding shares to investors within minutes or even seconds.

Amid growing competition at home, BYD hopes to increase its overseas sales and is currently building a factory in Hungary that is set to come online later this year. The automaker also has announced plans for a new plant in Mexico.