These indicators display the net change between a contract’s last stable price, and it’s most recent price. Remember, a contract and a market are two different, but related things.

In the Steyer example above, the arrows reflect changes in a single-contract market. It’s also very common to see multi-contract markets in which one contract’s price movements vary from that of the other contracts in the market.

So… what pushes these contract prices to change on PredictIt?

Well, remember that the price you see is the cost at which the most recent transaction– one trader purchasing shares from another– has taken place. More on trade dynamics here.

Such transactions depend on the highest price a trader is willing to pay for shares– and the lowest price another trader will sell them– at a given time.

Like economics, the prices offered in this supply and demand curve can depend on how traders react to various occurrences, such as a controversial tweet, or news of a high-profile political endorsement. For the remainder of this post, we’ll take a look at some of the most common of these occurrences to look out for.