IDXCarbon Trading Mechanisms: Auction, Spot, Negotiated, Marketplace

Updated 2026-11-02 · 4 min read · By the akar.earth specialist team

The four IDXCarbon trading mechanisms explained: Auction, Regular (spot), Negotiated Market and Marketplace, and which suits forest-carbon deals.

IDXCarbon offers four trading mechanisms: Auction, Regular Continuous Auction (spot trading), Negotiated Market and Marketplace. Auction suits primary allocation, Regular trading suits continuous price discovery, the Negotiated Market settles pre-agreed bilateral deals, and the Marketplace lets sellers list units at a fixed price.

What the mechanisms are

All four mechanisms trade the same two unit types: PTBAE-PU allowances and SPE-GRK offsets. They differ in how price is set and who initiates the trade. The descriptions below combine the exchange’s own list with a third-party practical guide. Session times, lot sizes, price limits and fees are set in the exchange rulebook and can change, so check the current IDXCarbon rules before trading.

Auction

The seller offers a fixed volume, and buyers bid at or above a floor price. Sources describe it as mainly used for primary-market allocation. For a project developer with a fresh issuance, an auction can establish a public price point. For the government, it is a way to sell units into the market in a structured way.

Regular Continuous Auction (spot)

The regular market matches buy and sell orders continuously on price-and-time priority, as on a stock exchange. SPE-GRK trades here as a standardised product, grouped by classification such as Nature-based Solution (NBS) or Tech-based Solution (TBS). Standardisation helps liquidity but hides project-level differences that matter to quality-focused buyers.

Negotiated Market

Buyer and seller agree price and volume off-screen and then report and settle the trade through the exchange. This is the natural route for offtake agreements, prepayment structures and corporate deals where the buyer has already done project diligence. Settlement on-exchange means the transfer is recorded through the exchange and registry process.

Marketplace

The seller lists units at a set price, and buyers purchase them. It works like a catalogue. For smaller buyers, it is the simplest way to buy and retire a specific project’s units without negotiating.

Who uses which mechanism

IDXCarbon’s service users fall into three categories: Compliance Company, Non-Compliance Company and Project Developer/Project Proponent. In broad terms:

• Compliance companies trading allowances use regular trading and auctions to balance their positions.
• Project developers selling SPE-GRK may use auctions or the Marketplace for new issuance, and the Negotiated Market for contracted buyers.
• Voluntary buyers, including foreign buyers since January 2025, use the Marketplace or regular market for smaller volumes and the Negotiated Market for contracted volumes.

Registration and onboarding are covered in how to become an IDXCarbon service user.

What the rules require

All trades sit under OJK’s carbon exchange regulation, POJK 14/2023 as amended by POJK 10/2026. Under the amendment, units traded on the exchange must be recorded in SRUK. Trades settle through the exchange, and ownership is updated in the registry. Retirement of SPE-GRK for an offset claim can also be done through IDXCarbon; surrender of PTBAE-PU for compliance cannot.

What it means for forest-carbon developers and buyers

Price discovery is limited. The exchange reports more than 1.9 million tCO2e of total volume and 10 listed SPE-GRK projects. With so few nature-based listings, regular-market prices for forest units may not reflect project quality. BeZero’s work on Indonesian projects shows prices rise roughly 40% per rating band, a differentiation that a standardised order book does not capture.

Negotiated deals remain central. Most serious forest-carbon buyers want to know the project, the community arrangements and the monitoring. That points to the Negotiated Market, with diligence done beforehand. See our carbon credit pricing guide for what drives value.

Marketplace listings need clear project information. If you list on the Marketplace, buyers see little beyond the listing. Strong project documentation and monitoring data help close the gap. Our dMRV implementation work produces the field-verified evidence buyers ask for.

Open questions

• Rulebook details such as minimum lots, price bands and fee schedules: read the current IDXCarbon rules rather than secondary summaries.
• Treatment of overseas units that POJK 10/2026 allows on the exchange: which mechanisms they can use is not clear from the sources we reviewed.
• Classification of units beyond NBS and TBS, and whether buyers will see vintage, methodology and project detail on-screen.

For the wider framework, return to the Indonesia regulation hub.