An over two-month rally in the shares of Thai billionaire Sarath Ratanavadi’s Bangkok-listed energy and telecommunications companies boosted the self-made tycoon’s fortunes by $6 billion.

Shares of power producer Gulf Energy Development surged 40% since the company announced plans in mid-July to merge with Intouch Holding, the biggest shareholder of Advance Info Service (AIS), Thailand’s second-largest mobile carrier by revenue. Intouch climbed 28% over the same period, while AIS rose about 21%.

The rally in Gulf Energy—Sarath’s biggest asset—helped boost the billionaire’s real-time net worth to over $15 billion from $9.2 billion when Forbes Asia published the list of Thailand’s 50 richest in July.

“The rally in recent months mainly reflected optimism that the merger deal will sail through and the expected synergy from consolidation of the two companies into a solid infrastructure play,” Rakpong Chaisuparakul, strategist at KGI Securities (Thailand). said. “Such healthy gains imply that positive prospects have, to a certain extent, been priced in.”

Shareholders of power producer Gulf Energy and telecom firm Intouch Holdings approved the proposed merger between the two companies controlled by Sarath, paving the way for the creation of an enlarged company with a market capitalizaiton of about $30 billion.

Gulf Energy has said that the combination will simplify the merged entity’s shareholding structure, increase efficiency, enhance business flexibility while creating a balanced business portfolio between energy, infrastructure, and digital businesses. Gulf Energy holds a 47.4% stake in Intouch.

According to separate filings to the Stock Exchange of Thailand, 99.99% of Gulf’s shareholders and 98.75% of Intouch’s shareholders present during the shareholders’ meetings on Thursday approved the planned amalgamation. The merger is expected to be completed in the second quarter of 2025.

As part of an overall restructuring, Sarath, Gulf Energy, Intouch Holdings and Singtel Strategic Investments—a unit of Singtel, the largest telecom company in Southeast Asia by revenue—will make a tender offer for a 36.2% stake in Advanced Info Service (AIS), a provider of mobile phone, broadband internet and digital services in Thailand, for 211.43 baht ($6.37) each. The offer price has been adjusted to factor in the 4.87 baht per share dividend paid by AIS in August. The transaction is expected to be completed in the first quarter of 2025.

Separately, Sarath, Gulf Energy, and Intouch will buy 58.9% of satellite operator Thaicom PCL, also controlled by a unit of Gulf Energy, at 11 baht apiece.

Gulf Energy, which was founded by Sarath in 2007, has been diversifying into telecommunications and digital businesses including data centers. In June, it partnered with Alphabet’s Google to build artificial intelligence-powered cloud facilities in Thailand. Earlier this year, Gulf Binance, a partnership between Gulf Energy and billionaire Chanpeng Zhao’s Binance, started a crypto currency exchange in Thailand.