JAKARTA, June 16 (Reuters) - Bukalapak, Indonesia’s No. 4 e-commerce firm, is keen to raise as much as $800 million in an IPO in August, two people with knowledge of the matter said, in what is likely to be the biggest by a startup in the Southeast Asian nation. Tapping a sharp pickup in investor interest in Southeast Asia’s rapidly expanding technology sector, Bukalapak is aiming to sell 10% to 15% of the company and wants a valuation of between $4 to $5 billion, they said. A confidential listing prospectus has been submitted to the Indonesia stock exchange, one of the sources added. Proceeds from the offering could range between $500 million and $800 million depending on investor demand and market conditions, according to the sources who were not authorised to speak on the matter and declined to identified. At the upper end of that target, it would be Indonesia’s biggest listing in 10 years. Bukalapak, which said in 2019 it was valued at more than $2.5 billion, did not respond to requests for comment. With a young population of 270 million, Southeast Asia’s largest economy has one of the fastest-growing online shopping sectors in the world. Indonesia’s e-commerce sector exceeded $40 billion worth of gross merchandise value in 2020, according to a June report by research firm Momentum Works, which estimates that Bukalapak holds a 7% market share. Reporting by Fransiska Nangoy, Gayatri Suroyo and Fanny Potkin; Editing by Sumeet Chatterjee and Edwina Gibbs Our Standards: The Thomson Reuters Trust Principles.