The Probably Stolen Underground Exchange is the black-market trade that runs through your trash can: you leave goods in the bin at night, and the exchange takes them and leaves something else behind. The Steam store page lists it as part of the advanced licenses you unlock, but the developer has not written a how-to, so this page puts together the official patch notes with the launch-week Steam guides and threads. Where a rule comes from one player or one guide, it is labeled that way.
How the Probably Stolen Underground Exchange works
A Steam Community guide by lpinch says the janitor unlocks the exchange and that it runs only on nights when the janitorial service is on. You leave the items in your trash can, the exchange takes them overnight, each trade happens once a night, and the payment appears in the trash can the next morning. A forum answer gives the same steps for a player who wanted to swap used filters: you need a Black Market standing better than -40, the janitorial service turned on, the goods in the bin, and a check of the bin the next morning. A Chinese-language reply in a second thread adds that you read the exchange list and drop the matching item into the trash.
Two patch notes bear on this. In the August playtest, at -40 reputation with the Black Market you keep access to the janitorial service, but its cost doubles. And Update 049 made the exchange for the smuggler bay take priority over the temporary exchange deal and updated the Underground Exchange Directive, the sheet that lists the trades, so it causes less confusion. A bug where Sawyer did not hand over the Directive if you took the Sawyer's Crew starting perk without skip-intro mode was fixed in the same build. One Rock Bottom player picks Sawyer's Crew for access to the exchange without the janitorial fee; see Probably Stolen Rock Bottom.
Trades listed by the Chemist guide
These trades come from lpinch's Complete Chemist Guide, which says it was checked against build 100-Rev5. They are about Dream Dust and poison, but the structure shows how the exchange works.
| Trade | What you leave | What you get |
|---|---|---|
| Dream Dust x2 | Two vials with 60% combined purity | One random item such as a water filter, ingot, electronics, medical supplies or food; at 120% combined, double that plus a small chance at rarer rewards like a full battery |
| Poison x2 | Two vials (Nightmare Dust counts) | An Energy Credit battery charged to half the combined purity, capped at 100 |
| Dream Dust x4 | Four vials of any purity | Medical items by average purity, from about 15 in value below 30% up to about 520 at 99% and above |
The x4 trade is a promotion that the guide says runs roughly three weeks in seven, and it goes first, so four vials in the bin get that trade instead of the x2 one. The guide's point is that trades do not add to your case value, which is why it calls the exchange a way to turn contraband into legal goods. By its numbers the x2 trades are worth less than selling the same extract as Pharma grade, so use them for leftovers; four Lab Pure vials sell for about 310 and raise your case value, while the x4 trade pays about 520 in goods. How case value becomes a fine or an arrest is explained on the Probably Stolen Chemist page and in Probably Stolen contraband.
Smuggler Bay Mod delivery and trash risks
The exchange also delivers the Smuggler Bay Mod. Hotfix 1.0.0.5 stopped that mod from being thrown out with the trash when you leave it in the can overnight. Launch-day reports in a Steam thread add that a payment left in the can past the next day is discarded, and that extra items in the bin can be swapped or lost during a trade: one player put in a Smuggler Bay and eight oxymore injectors with other tickets, got a different item back and lost the rest, then got the right result on a second try with only the required items. The developer replied in that thread, and the contraband page covers the planned safeguard. Until then, collect the payment first thing in the morning and put in only what the trade needs.
Unlocking and next steps
The exchange is tied to your standing with the black market, so watch your Black Market reputation before you rely on it, and read Probably Stolen tips and tricks for the first-week basics. If you are hiding goods rather than trading them, a Smuggler Bay is the other tool, and the Probably Stolen radioactive waste page explains why the trash bin does not solve everything. All changes are tracked in Probably Stolen patch notes.
Probably Stolen Underground Exchange FAQ
How do you use the Underground Exchange in Probably Stolen?
Turn the janitorial service on, put the goods listed on the Directive in the trash can, and check the can the next morning. The exchange takes one trade per night.
Why does the Underground Exchange not respond?
Check your Black Market reputation, which should be above -40, and that the janitorial service is on. Items must be in the trash can, not in a container the exchange cannot reach.
Does the exchange add to Security's case against you?
The Chemist guide says exchange trades do not add to your case value, unlike selling contraband to a customer. That is a player guide's reading, not a developer statement.
Where do you get the Underground Exchange Directive?
Update 049 says Sawyer gives it, and that the Sawyer's Crew starting perk was fixed so it still works without skip-intro mode.