A $500 bet from a casual account is noise. A $50,000 position from a wallet that has been profitable across dozens of resolved markets is signal. The hard part is telling them apart while the trade is still fresh, and that is where prediction markets are strangely generous compared to almost any other venue.
Spotting informed flow
Informed traders leave footprints. Bigger sizes, tighter timing around catalysts, consistent direction. On a blockchain-based venue like Polymarket you can see the actual wallet behind every trade, so a wallet with a long record of profitable resolved positions carries more weight than one placing its first bet. That is a data source most markets simply do not give you.
Timing matters as much as size. An informed trader usually positions before the news breaks, not after. If a large buy hits a political contract 30 minutes before a story lands, that sequence is worth writing down. It is not necessarily insider trading in any legal sense, but someone had better information or ran the analysis faster.
Watch for what does not happen too. A big headline drops and the price barely moves? The informed money already priced it. The news is only news to the part of the market that was not paying attention.
Block trades vs slow accumulation
Large positions tend to show up in two shapes. A block trade is one big order that moves the market on the spot. It signals urgency, someone who wants the exposure now and will eat the slippage to get it. In prediction markets these often land right before an event resolves, when the trader is very confident about the outcome.
Algorithmic accumulation is the opposite temperament. The position gets sliced into many small orders spread over hours or days to keep market impact low. It is harder to see but more common among the sharper players. You catch it by watching for a steady, one-directional stream of similarly sized orders from the same wallet or a cluster that moves together.
The difference changes how you react. A block trade creates an instant move that can snap back if the trade was wrong. Slow accumulation builds a quieter trend that is genuinely hard to fade for profit.
Retail vs institutional habits
Retail traders lean on round numbers like $100, $500, $1,000, react to headlines instead of anticipating them, and pile into the popular contracts with heavy media coverage. Sophisticated participants use odd lot sizes tuned to specific price levels, trade several correlated contracts at once, and often work the quieter markets where the edge is fatter.
When the two disagree, the institutional side has historically been the better tell. A contract where retail is hammering YES while the seasoned wallets quietly accumulate NO is a real warning on the YES thesis.
Divergence across platforms
When the same question trades in more than one place, comparing flow across them adds a whole dimension. Polymarket showing heavy YES buying while Kalshi sits flat or slightly bearish might just reflect different crowds, or it might be a genuine mispricing on one side. Either way it is information.
Cross-platform flow is one of the few durable edges I trust in prediction markets. The catch is you have to watch several venues at once, which is a chore by hand and a big part of why we built aggregation into Blockcircle in the first place.
Building the habit
Start small. Track the biggest trades in whatever market you are already watching, and log the wallet, the size, the timing against the news, and how it actually resolved. Do that for a few weeks and you build a feel for which patterns predict and which are just noise. It is slow, and it is one of the few advantages in this game that does not evaporate the moment someone else notices it.