Trading on the Grand Exchange
- Open the exchange at a Grand Exchange clerk and choose an item, a quantity and a price per item.
- When you confirm, you pay up front: coins for a buy, the items for a sell. An offer can fill the moment it is placed, so it has to be funded first.
- Your offer fills against every waiting offer that crosses it, best price first, and oldest first among equal prices.
- Each fill settles at the waiting offer’s price. If you bid more than you had to, the difference comes back to you.
- Coins and items wait in the offer’s collection box until you collect them. Both sides update even when the other player is offline.
Aborting an offer returns the part that never traded. Anything already traded stays in the collection box. Ironmen cannot use the Grand Exchange.
How prices move
Nothing on ONYX sets a price except players. There are no NPC buyers or sellers on the exchange and no staff price list: every trade has a player on each side, and you can offer any price you like. The guide price is the exchange’s running estimate of what an item is worth, built from two things players do.
1. Trades set the guide price
The guide price is the average price of everything traded, weighted by quantity. Each fill adds its items at the price they sold for, so a big trade moves it more than a small one.
| What happens | Guide price |
|---|---|
| Starting point: 40 traded, averaging 15,000 | 15,000 |
| Someone sells 10 at 17,000: (40 × 15,000 + 10 × 17,000) ÷ 50 | 15,400 |
Guide prices started from a one-time snapshot of official Old School prices, and that snapshot counts as a single trade. The first few trades of an item therefore move it a long way, and an item nobody has traded yet still shows its snapshot price.
So that busy items keep reacting, the average only remembers so much. Once an item’s traded quantity passes a limit, its history is shortened to a tenth of that limit, all at the current price, so new trades count for more again. The limit is 10,000 items for things under 25,000 gp, 2,500 up to 100,000 gp, 1,000 up to 1M, and 500 above that.
2. Waiting offers pull it toward them
A price can be wrong when nothing is trading, so the exchange also looks at the offers waiting on the book. Once a minute, for every item with waiting offers:
- If someone is bidding above the guide price and nobody is selling that low, it moves up toward the best buy offer.
- If someone is asking below the guide price and nobody is buying that high, it moves down toward the best sell offer.
- Each step closes a quarter of the gap, and never more than 5% of the price.
In the example, a buy offer waiting at 18,000 with no sellers lifts the guide price minute by minute: 15,400, 16,050, 16,537, 16,902, 17,176, getting closer to 18,000 each time. It never passes a real offer, so no one can push the price past what somebody is actually willing to pay or take.
What this means when you trade
- To trade now, offer at or past the best waiting offer on the other side. You pay or receive the waiting offer’s price, not yours, so bidding high to fill fast costs nothing extra.
- To get a better price, offer between the best buy and best sell offer and wait for someone to come to you. A waiting offer beyond the guide price also pulls the guide price toward it.
- The guide price is not a limit. It is only where the price button starts. Any price is allowed, and the exchange page shows the best waiting offers next to it.
The guide price button, the exchange window, death piles and price checks all read the same value, so every price you see in game agrees with what the exchange would pay.
Buy limits
Each character can buy a limited quantity of each item every four hours, on a rolling window. The limits are the official Old School ones. Aborting a buy gives back the part of the limit it never used. Selling has no limit.
Tax and the treasury
Sellers pay 5% of every fill. 60% of that tax is destroyed. The other 40% goes into a treasury pot the server can pay back out. Your collection box always holds what you receive after tax.
For items worth more than about 100M each, the exchange window shows at most 5,000,000 gp of tax per item. The server still charges the full 5%.
GP burn
GP burn is coins removed from the game for good. Two things burn GP on ONYX: the destroyed share of exchange tax, and the Good Deed Well, where every 25,000 gp buys a lottery ticket. Half of each week’s well burn is shared by the tickets on the winning line, so the well removes the other half. How the lottery works.