As in the real world, trading means swapping resources and money. Trading is paramount in CXL, because the entire game economy is designed around the need to swap resources - it's impossible for a city to be completely self-sufficient. So, basically, trading means that you sell your excess production (that your city doesn't need) and buy the resources that your city needs, but doesn't produces.

History[]
The initial idea of trading was in the heart of the Planet Offer - the opportunity to swap resources with other live players across the 'globe'. There was an in-game 'market' where you could post trade offers by specifying a resource, N of Tokens you offer, and how much cash you want. You could also post 'buy' offers, where you ask a specific resource, its amount, and how much cash you offer. Every offer had an expiration date. You could also trade directly with a player, outside 'the market'.
Once an offer got accepted, it resulted in establishing a Trade Contract, where two cities swapped their resources for cash for a limited amount of time (5 days real time). This was also the biggest hitch of the system - you constantly needed to reevaluate your contracts, to make new ones, to stay online and keep track of everything. Otherwise, you risked a cascading crash, where one key contract termination could lead the entire city to bankruptcy.
Needless to say, this was the most heated part of the online activity in the game, with constant changes in the market prices, people trying 'dumping', bargaining, etc. We also had speculation, frustration, and towards the end of the second month we started seeing cartels forming, trade 'unions' that sought to equalize the prices of goods on a Planet. And then the PO ended.
Fortunately, MC decided trading is too paramount to be left behind in the planned Single player conversion, so they redesigned the trading system in its current form. Now you can trade with your own cities, as well as Omnicorp, creating a virtual economic empire on your Planet. There is no more contract termination - once established, trades are permanent, unless production in the exporting city decreases for some reason.
Prerequisites for trading[]
So, what do you need to trade? The following:
1. Trade capacity[]
This means available freight and passenger capacity from your city links/airports/seaports. Every token you want to trade uses up part of this capacity (one unit per each token), with the exclusion of electricity, which you currently trade for free. Note that the in-city freight and passenger services quality doesn't have anything to do with external trading - it affects other aspects of the economy, as explained before. Resources are divided in what type of trade connection they require - freight (goods-related resources, such as Fuel, Water, Industry), or Passengers ('life' resources like Office Services and Holidays). You need to expand your city's trading capacity according to what resources you trade the most, but most of the Inter-City Links provide both types of trading capacity.
2. Cash tokens[]
Technically these represent the money flow used in trading. You'll basically use cash tokens in every transaction with Omnicorp, whether giving them to buy stuff, or receiving them when you sell your production. Each cash token=100 cash, BUT - only your cash flow is used in determining that, not the entire city budget! In other words, if you want cash tokens, you need to maintain POSITIVE cash flow.
When trading between cities, you don't need cash tokens (you could give or receive other resources even if your cash flow is negative). But you could also make 'financial transactions' between the cities - swap cash tokens. In this case, of course, the city that gives needs to have a positive flow, which turns into cash tokens.
Trade mechanics[]

Trade is conducted on the Trade screen, accessible both from the City (from the Main menu), and from the Planet:
The screen is divided in to halves, representing the two sides of the trading process. On the left side, you could select either one of your cities (the City you're currently playing will be selected by default here), and on the right side you can select other cities, or Omnicorp, as the trade partner.
Right below the city names you will see their current trading capacity (determined by their City links), and then the individual tradeable resources. The different columns show the following details about that resource trade: (from left to right)
- Total production of the resource in that City
- N of tokens currently used in Megastructure projects
- Total trade for that resource with partners other than the one currently selected
- Trade for that resource with the current partner
- Net balance for that resource in this City
Between the two partners, you will see sliders (one for each resource), and arrow buttons at both ends of the sliders. They are the interface that allow you to control trading amounts. The white numbers in the center above each slider will show the net trade amount per resource - a positive number means the left city is exporting tokens, while negative number means that it is importing. To adjust trading amounts, either grab and move the slider, or use one of the arrows on either side.
Selling[]
In order to sell, or export, you first need at least one positive token of the resource (that is, overproduction that your city doesn't need). To sell your excess, go to the trade screen (which I like calling 'the market' - a leftover from the Planet offer, I guess), select the city you want to trade with (or Omnicorp), and move the slider of the relevant resource towards the second city (alternatively, click on the arrow on the right side of the slider). If you trade with Omnicorp, you'll sell for real, and receive cash tokens in return. In the case of your cities, you just use up freight/passenger capacity. Be warned that if in the course of the game production of the resource you're selling decreases (or if internal consumption increases), the game will automatically adjust the traded amount, which might affect your Budget! Always keep an eye upon the resources you sell, and try to maintain a couple of tokens of excess so that you don't get nasty surprises.
Buying[]
The opposite of selling. Works the same way, only you'll move the slider towards the original city (or click the left arrow). If you're buying from Omnicorp, you'll need cash tokens to buy stuff, and a lot of them! Reminding again that cash tokens represent the positive cash flow of your Budget, and if that cash flow suddenly goes negative (because of that shiny new metro line you just built, for example), Omnicorp imports will get cancelled!
Financial transactions[]
You can also swap cash tokens between your cities, effectively transferring part of your positive cash flow to another city. Again, this will last until you have enough cash tokens available. Using these transfers, you could actually set your own price for resources when traded between cities.
Trading tips[]
After the end of the Planet Offer, trading becomes more of a single empire management - a single city won't be self-sufficient, but several cities will complement each other with resources. So, as a tip N 1:
- Always develop at the same time several cities specialized in different resources, complementing each other.
You always have Omnicorp as a potential trade partner, but the prices of the resources they sell are exorbitant, so Tip N 2 is:
- Buy from Omnicorp only as a last resort.
So, most of the trading will happen between your own cities. It sounds simple, but it is from simple - you have to think of the freight/passenger trade capacity of each city; developing different resources across your 'empire'; selling to Omnicorp when you need cash; transferring cash from more successful cities to others.
In the ideal situation all the resources your cities need will be provided by other cities. However, it doesn't always happen like this. The biggest danger is not to be able to afford the maintenance fees in some cities (not enough cash). Remember that Omnicorp is not omnipotent - its cash is limited, and you can't use it as a cash resource indefinitely by selling to them outrageous amounts across your empire. So, tip N 3:
- Don't depend entirely on Omnicorp for cash.
Instead, transfer cash from cities that have too much to others that need it. Also, always develop private taxable businesses, even in cities where your concept doesn't fit them - the taxes earned are 'bonus', they don't diminish other cities' or Omnicorp's cash reserves.
Doing all this, across several cities is quite a challenge. Managing the shortages in each with the surplussed of the others, while IN THE SAME TIME selling to Omnicorp for cash. Anybody that thinks this is easy.... think again. Especially when you start building MegaStructures.
To summarize:
- The key to successful trading lies in thinking strategically and not depending too much on selling to Omnicorp.
- NOTE: There are some bugs in the trading engine of the game. Sometimes you get cash 'for free', or you get much more than you should, and then later all of a sudden you lose it... Most of these problems can be evaded if you use the sliders in the Trade panel as few times as possible (instead using the arrows for transactions).