The price of bitcoin on the CoinDesk USD Bitcoin Price Index fell more than 13% today to reach a seven-day low of $329.12.

At press time, bitcoin was trading at an average of $332.89 across major USD bitcoin exchanges, a 13.16% decline from the day’s opening of $380.04.

The day’s most rapid decline began at 20:15 UTC before falling abruptly one hour later.

Similar price movements were observed on the CoinDesk CNY Bitcoin Price Index, which at press time, indicated prices had fallen more than 12% across major China-based exchanges including BTCC, Huobi and OKCoin.

Data suggests both USD and CNY markets are now moving in tandem, as prices saw the most notable downward movement at 21:25 UTC. The value of bitcoin was still higher on CNY exchanges, where one bitcoin was trading for around $344 at press time.

The declines follow a US government auction of roughly 44,000 BTC last Thursday and come amid increasing reports that last week’s price increases were driven by MMM Global, a pyramid scheme that has captured the attention of The Financial Times and its coverage of market movements.

According to the FT, MMM ringleader Sergey Mavrodi has claimed credit for the price increase due to the use of bitcoin in transactions for MMM-China, where bitcoin is the only payment method offered to users.

The connection has been further established by public statements from executives of major China-based bitcoin trading firms, though blockchain evidence of this impact has yet to conclusively validate the claims.

CoinDesk has reached out to blockchain analysis firms for more information on last week’s price movements, though no further details had been provided as of press time.

At publication, the price was also down roughly $30 year-over-year, as bitcoin opened at $366.99 on 11th November, 2014.

Price decline image via Shutterstock