SYDNEY - The Chinese mainland's electric vehicle maker BYD said on Tuesday it had raised $5.59 billion in a primary share sale that was increased in size, making it the largest of its kind in the Hong Kong Special Administrative Region in four years.

The company said it sold 129.8 million primary shares in the deal, up from the original 118 million shares planned when the deal launched on Monday.

BYD's shares in the HKSAR opened down 8 percent on Tuesday, in line with the discount the stock was sold at in the deal, while the Hang Seng Index was off 1.5 percent.

BYD said the transaction was the largest equity follow-on offering globally in the automotive sector in the past decade.

The United Arab Emirates-based Al-Futtaim Family Office was a key investor in the share sale, and the two firms were planning on forming a strategic partnership, BYD said. It did not say how much the family had invested.

Most automakers on the Chinese mainland have eyed the Middle East to grow their overseas sales in recent years.

Leveraging its competitive lineup of affordable battery-powered vehicles, BYD has emerged rapidly to be the mainland’s largest automaker since 2022.

Over 90 percent of BYD’s total sales of 4 million cars in 2024 were on the mainland, where it accounted for more than a third of the total sales of pure electric and plug-in hybrids in the world's largest auto market.

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BYD sold the shares at HK$335.20 ($43.11) each, a 7.8 percent discount to the stock's closing price of HK$363.6 on Monday.

The shares were marketed in a price range of HK$333 to HK$345 per share each in the accelerated book build.

BYD's share sale is the largest of its kind in the HKSAR since 2021, when Meituan raised $6.9 billion, according to LSEG data.

BYD's shares in the HKSAR have risen 36.38 percent so far this year while its Shenzhen-listed listed stock has rallied 27.4 percent on the back of the improved tech sector sentiment.

The company plans to use the proceeds to invest in research and development, expand overseas businesses, supplement working capital, and for general purposes.

The automaker has been accelerating its expansion to add production facilities and is hiring more workers as it targets to sell 5 million to 6 million cars in 2025, on par with General Motors and Stellantis globally. BYD said it had nearly 1 million employees as of early September, more than Toyota and Volkswagen AG each had.

BYD in February launched 21 models of electric and plug-in hybrid models cars priced from $9,555 to be equipped with its God’s Eye smart driving system to stay competitive at home.

It has also been ramping up export efforts, with Brazil its largest overseas market in 2024. In Europe, the automaker has launched new hybrid models as its EVs face an additional 17 percent tariff in the region.

READ MORE: Chinese carmaker BYD revs up Brazil's enthusiasm for EVs

A Citigroup analysis said BYD raising the money offshore in the HKSAR would allow the company to expedite its international business plans.

Goldman Sachs, UBS and CITIC Securities led the BYD deal.