FAISALABAD, Pakistan — Interloop Ltd., which makes socks for Nike and Adidas, is planning Pakistan's biggest ever initial public offering by a private firm.The company plans to raise as much as ₹6.8 billion ($51 million) to expand its sock manufacturing capacity by around 20 percent and enter the denim business, said chairman and co-founder Musadaq Zulqarnain. It will offer 12.5 percent of the business in the sale, likely to take place in January, and is aiming to lift revenue by 77 percent over five years, he said.“Our capacity is already full,” Zulqarnain said in an interview at the company’s head office in Faisalabad. Interloop can see more growth, so will “take that risk” to expand, he said.The listing comes as Prime Minister Imran Khan tries so spark an export revival to make up ground that Pakistan has lost to low-cost manufacturing destinations like Vietnam and Bangladesh. The new government has announced plans to cut gas and electricity prices to support companies selling abroad, although the push has been criticised for relying too much on subsidies.Imran Khan’s answer to Pakistan’s ailing exports? More subsidies.The Interloop offer will surpass the previous record for a private company, when Pakistan Stock Exchange Ltd. raised ₹4.5 billion ($34 million) two years ago. There have been larger sales by state-controlled companies in Pakistan.Interloop was founded in the early 1990s by Zulqarnain and his brother, chief executive Navid Fazil. The company now employs around 16,000 people and makes more than half a billion pairs of socks a year. Revenue for the 12 months through June was ₹31 billion ($232 million), according to Zulqarnain.“They are one of the most well managed companies in Pakistan, so they should not have a problem with demand,” said Amjad Waheed, chief executive at NBP Fund Management Ltd. in Karachi. “Investors are sitting with cash on the sidelines after the market drop over the past year.”By Faseeh Mangi; editors: Arijit Ghosh, Andrew Janes, Chris Kay.