Bitcoin extended its recent tumble from record peaks after one of China’s biggest bitcoin exchanges announced plans to halt trading at the end of the month, the Financial Times reports. The cryptocurrency tumbled as much as 11.3% to $3,426.92. It has fallen now for seven days in a row in its longest losing streak in a year. Thursday’s fall came after BTCChina abruptly said it would “immediately stop accepting new account registration[s]” and then halt all trading on September 30. On its website, the exchange quoted bitcoin as down almost 20% against the yuan. BTCChina ranks among the biggest bitcoin exchanges. The news adds to concerns that China, a large market for the currency that is mined using computer algorithms, may be looking to crackdown heavily on cryptocurrencies. The People’s Bank of China earlier this month outlawed initial coin offerings, which are a tool used by start-ups in lieu of traditional funding sources, such as venture capital.