Polkadot's main online line is approaching, some exchanges DOT futures prices have plummeted

The Polkadot main online date is approaching, and some exchanges that have launched the futures Polkadot token DOT have plunged, with the Hotbit exchange plunging 30%.
At the Polkadot China Tour event in June 2019, Dieter Fishbein, co-manager of the Web 3 Foundation, said that the Polkadot main network is scheduled to go online at the end of 2019 and will be online at the latest in early February 2020.
According to previous reports, Polkadot first tested the network has been running normally, the number of nodes exceeds 100, and the transfer test will be started soon. However, Polkadot officially did not announce the specific launch time.
After inquiry, it was found that the Polkadot futures DOT tokens were traded on the exchanges of Hotbit, Lbank and Bigone. Because there is currently no tradable DOT for transfer transactions, investors cannot withdraw futures tokens in their hands, resulting in large spreads between different exchanges. Among the exchanges such as HotBit and LBank, the declines were the most significant, -30% and -5% respectively.