What a price actually means
The price of a contract reads as a probability. A Yes contract at 40¢ means the market puts a 40% chance on that outcome. A contract at 85¢ means 85%.
How prices are set
Prices aren't set by Lumina — they emerge from trading. When more people buy Yes, the price rises. When more people sell, or buy No, it falls. Every trade is someone expressing a view on whether the current price is right, and the price adjusts to reflect it.
Contracts are priced in 1¢ increments between $0.02 and $0.99; these bounds are set by exchange rules. A contract trades within that range while the market is open and settles at exactly $0 or $1 when the outcome is decided.
What the price tells you — and what it doesn't
A price is the market's best estimate given the information currently being traded on. It isn't guaranteed to be right. Two situations where prices can mislead:
Thin markets. Where few people are trading, the price may reflect a small number of views rather than a genuine consensus. A 70¢ contract in a low-volume market carries less information than a 70¢ contract in a heavily traded one.
Stale prices. Major events — a data release, a policy announcement — can move a contract sharply in seconds. Between events, a price can sit stale. If you have information the market hasn't absorbed, the current price may not reflect it yet.