Amman Mineral Appoints Arief Sidarto as CEO, Replacing Alexander Ramlie Amid Market Jitters
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JAKARTA, investortrust.id — Indonesia’s leading copper and gold miner PT Amman Mineral Internasional Tbk (AMMN) has named Arief Widyawan Sidarto as its new president director, succeeding Alexander Ramlie, who resigned ahead of the company’s annual general shareholders meeting (RUPST) in Jakarta on Monday, June 16, 2025.
Sidarto, who previously served as the company’s chief financial officer for over eight years, said the leadership transition marked a strategic move aligned with Amman’s long-term vision of sustainable growth, operational excellence, and lasting impact.
“It is an honor and a privilege to lead Amman into a new chapter of growth and transformation,” Sidarto said in an official statement. “What truly makes Amman special is its people. We have a team full of talent and resilience.”
Before joining Amman, Sidarto was a managing director and board member at Rajawali Corpora, a diversified Indonesian investment group with interests spanning mining, palm oil plantations, luxury properties, transportation, infrastructure, and media. Earlier in his career, he led investment banking operations for Goldman Sachs in Southeast Asia. Sidarto holds dual bachelor’s degrees in finance and engineering from the University of Pennsylvania, graduating summa cum laude, and an MBA from Harvard Business School.
As part of the leadership reshuffle, the shareholders also approved Ramlie’s appointment as commissioner and named Aditya Sasmito as director. Sasmito has served since 2020 as a director at AMMN’s subsidiary, PT Amman Mineral Nusa Tenggara (AMNT).
Stock Dives on Leadership Shift
Despite the strategic rationale behind the transition, AMMN’s shares plummeted on the Indonesia Stock Exchange (IDX), closing down Rp 625, or 7.62%, at Rp 7,575. During intraday trading in the first session, the stock had briefly soared by 12.5% to Rp 9,225 before reversing course.
According to IDX data, AMMN, along with BRMS, posted the steepest losses among gold and copper mining stocks during the day. By contrast, ARCI managed to gain 4.85%, closing at Rp 540.
The market reaction came amid concerns over the company’s financial performance. In the first quarter of 2025, AMMN reported a net loss of $137.63 million, a sharp reversal from a net profit of $130.72 million in the same period last year. The loss reflected a dramatic collapse in net sales, which fell from $601.55 million to just $2.12 million. The most significant decline came from gold sales, which dropped from $291.17 million to $1.87 million.