A sell-off sent the ethereum price plunging below $300 on Monday, forcing the second-largest cryptocurrency to its lowest mark in more than nine months. Ethereum had traded as high as $323 earlier in the day, but a flurry of sell orders began to pummel the market at approximately 15:00 UTC, driving ETH closer and closer to $300, a level it had not touched since 2017. ETH/USD | BitfinexAt 15:43, ETH closed just pennies above $300, and less than one minute later it fell below that mark on Bitfinex for the first time since Nov. 12. As of 16:45 UTC, the ethereum price had dropped to $293. Ethereum is now down seven percent for the day and more than 61 percent in 2018. ETH/USD | BitfinexNotably, this decline has not just occurred against the dollar, as the ethereum price has also cratered against bitcoin. Just six months ago, ETH was valued at just under 0.1 BTC. Now, it’s priced at less than half that mark and shows no signs of finding its footing as bitcoin continues to gobble up market share. ETH/BTC| BitfinexAt a present value of 0.047, ETH/BTC is now trading at levels not seen since mid-December, when the bitcoin price went parabolic and briefly peaked at $19,891 on Bitfinex. It’s not entirely clear what drove the sell-off, which is disproportionately large compared to the minor declines exhibited throughout the majority of the rest of the cryptocurrency market. Click here for a real-time ethereum price chart