Nikolas Kokovlis | Nurphoto | Getty ImagesPrediction markets platform Polymarket is expanding into trading of perpetual futures contacts, the company said Tuesday.The announcement comes on the heels of a report from The Information that its main rival Kalshi has plans to offer crypto trading, including perpetuals. These are futures contracts that stay open indefinitely, allowing traders to hold leveraged exposure and exit anytime they want as long as they have enough funds to maintain it.Polymar...