Enlarge (credit: Bitcoin Charts)

Six weeks ago, it looked like Bitcoin’s latest boom might be coming to an end. The virtual currency had been worth almost $5,000 in early September, but then Chinese regulators announced a harsh crackdown on China’s Bitcoin economy. On September 15, Bitcoin’s price reached a low of $3,000.

But then the currency bounced back, and it has been on a tear ever since. Last night the price of one bitcoin soared about $7,000 for the first time—that’s a ten-fold increase over the last year.

It’s never easy to pinpoint exactly what’s driving market optimism about Bitcoin, and this case is no exception. A major factor in Bitcoin’s growing value over the last year has been the broader popularity of initial coin offerings—sales of new Bitcoin-like cryptocurrencies. Because it’s not easy to set up an exchange for trading a new currency for dollars, most ICOs are conducted using bitcoins or Ethereum’s ether as an intermediary—customers buy those currencies first and then trade them in for the new token.