Sarath Ratanavadi, founder and CEO of Gulf Development. © 2024 Bloomberg Finance LPThai billionaire Sarath Ratanavadi has increased his stake in Gulf Development as partner Singtel sold S$1 billion ($771 million) shares in the Bangkok-based energy and telecommunications company.Singtel said it sold a 2.8% stake in Gulf Development to institutional investors through a private placement, generating exceptional gains of about S$140 million, as the Singaporean telecom giant seeks to cash in and reallocate capital to fund growth and shareholder dividends. After the transaction, Singtel will retain a 4.95% stake in Gulf Development, valued at around S$1.8 billion, according to a statement released by Singtel on Tuesday.“This divestment underscores Singtel’s concerted efforts to optimise our portfolio as we continue our disciplined approach to capital management,” Arthur Lang, chief financial officer of Singtel said in the statement. “Gulf Development’s share price has performed strongly since listing, providing an attractive opportunity for Singtel to crystallise value and reallocate capital towards growth and driving shareholder returns,” Lang said.According to a separate filing with Thailand’s Securities and Exchange Commission, Sarath, through Gulf Holdings, bought 33.5 million shares at 59 baht each, spending a total of 1.97 billion baht ($59 million). The purchase increased Gulf Holdings’ stake in the company to 4.2% from 3.9%. Including his direct and indirect holdings, Sarath now owns about 60% of the company.Singtel acquired a 7.7% stake in Gulf Development in 2025 after the merger of Intouch Holdings and its largest shareholder, Gulf. The deal simplified Singtel’s investment in its Thai associate, Advanced Info Service (AIS), one of the nation’s largest mobile carriers, and created a new entity, Gulf Development, which is among Thailand’s biggest privately held power producers.MORE FOR YOUDespite selling part of its stake in Gulf Development, Thailand remains a key market for Singtel. “We continue to have a strong partnership with Gulf Development through our joint investment in AIS and our data centre venture,” Lang said.With a real-time net worth of $17 billion according to Forbes’ data, Sarath is among the wealthiest in Thailand. Sarath, who founded Gulf in 2007, continues to eye new ventures.In 2024, the company joined with Google Cloud to build AI-powered cloud facilities in Thailand while its joint venture with Binance, cofounded by Changpeng Zhao, launched a cryptocurrency exchange in the country. AIS is also part of a consortium that secured approval last year to set up a virtual bank.