Because all mature exchanges have price limits. Even when stock is traded on multiple exchanges. Sometimes these limits are 1/2x and 2x of average/opening/auct

Because all mature exchanges have price limits. Even when stock is traded on multiple exchanges. Sometimes these limits are 1/2x and 2x of average/opening/auction price, sometimes are very tight. Some exchanges stop trading given security for the day, others are recalculating these limits in almost real time and stop for a couple of minutes max. All these safeguards are there for a reason. And some site positioning themselves as “exchange” and not reversing/pausing (or at least ivestigating) tells only about their maturity.