Glossary
YES/NO shares
The two tokens in a binary Polymarket market. YES pays $1 if the outcome happens; NO pays $1 if it does not. A complete set mints from $1.
Every binary Polymarket market is two tokens: YES and NO. YES pays $1 if the stated outcome happens; NO pays $1 if it does not. You can buy either side. You do not short YES in the stock-market sense — you just buy NO, or sell YES you already hold.
A complete set (one YES + one NO) can be split from $1 of collateral and merged back into $1, which is why the two implied probabilities plus the spread should orbit 100%. If YES is 0.34 you should expect NO near 0.66 on a functioning book. Gaps larger than the spread usually mean one side is stale or you are looking at a NegRisk leg rather than a simple binary.
Share count is the position. Paying $340 for 1,000 YES at 34¢ is 1,000 contracts; if it wins, payout is $1,000 and profit is $660 before taker costs. The payout calculator does that arithmetic; it is not an order ticket. Read the token, not just the chart. Our tape can show a print on the NO token at 70¢ that looks like a “70% YES” if you ignore which share moved — a common research error.