Anyone who says they have reinvented an old idea is inviting suspicion(招致怀疑). But if the idea concerns money, it is wiser to skip the suspicion and back away(后退，退缩) immediately. This is because “I have reinvented an old financial idea” means “I am about to take your money if you give me half a chance.”(这是因为“我重新发明了一个旧的金融理念”意味着“只要你给我半点机会，我就要拿走你的钱。”)
任何声称自己重新发明了旧想法的人都会招致怀疑。但如果这个想法关乎金钱，明智的做法是跳过怀疑，立刻退避三舍。这是因为“我重新发明了一个旧的金融理念”意味着“只要你给我半点机会，我就要拿走你的钱。”
Perpetual futures were first traded in 2016 by Arthur Hayes, who co-founded the BitMEX exchange for cryptocurrency derivatives(衍生品). Derivatives are financial contracts. Some have finer points(细节，微妙之处) that make even most traders’ eyes glaze over(眼神呆滞，感到厌倦); traditional futures, though, are pretty simple and have been around for centuries. A future is an agreement to buy or sell something for an agreed price, on a set expiry date in the future. At the Dojima Exchange(堂岛交易所（日本大米期货市场）), in 18th-century Japan, they were used to trade rice. Since then, they have been applied to everything from corn to electricity. Ten years ago, Mr Hayes reimagined them as a means for betting on bitcoin. Attentive readers can perhaps guess where this is going.(细心的读者或许能猜到接下来会发生什么。)
永续合约于2016年由Arthur Hayes首次交易，他是加密货币衍生品交易所BitMEX的联合创始人。衍生品是金融合约。有些合约的细节之精细，连大多数交易员都会感到困惑；不过，传统期货相当简单，已经存在了几个世纪。期货是一种协议，约定在未来某个到期日以约定价格买入或卖出某物。在18世纪的日本，堂岛交易所曾用期货交易大米。自那以后，期货被应用于从玉米到电力的各种商品。十年前，Hayes先生将其重新构想为押注比特币的工具。细心的读者或许能猜到接下来会发生什么。
Mr Hayes’ innovation was to ditch(抛弃，丢弃) the expiry date. To make sense of(理解，弄明白) this, think of an old-school future not as a contract to trade the underlying asset(标的资产), but as a bet on its price. If this rises after the future is agreed, the “long” side is in profit, since it is due to buy the underlying asset for less than market value. Its mirror image, the “short” side, is in the red(亏损，赤字) by the same amount. Conversely, if the price falls, the long loses and the short wins. Parties to a perp(永续合约的简称)etual future (or “perp”) sign up to roughly this profit-and-loss structure, without agreeing to actually trade the underlying asset.
Hayes先生的创新在于取消了到期日。要理解这一点，不妨将传统期货视为对价格的押注，而非交易标的资产的合约。如果期货协议达成后价格上涨，“多头”方获利，因为它将以低于市场价的价格买入标的资产。其镜像面“空头”方则亏损相同金额。反之，如果价格下跌，多头亏损，空头盈利。永续合约（或称“perp”）的参与方大致接受这种盈亏结构，但无需同意实际交易标的资产。