Bitcoin prices tested three-month lows Monday after Britain's Lloyds Banking Group Plc  (LYG) joined a growing list of lenders that have banned cryptocurrency purchases on credit cards amid an expanding crackdown on digital currencies that has loped more than $400 billion in global market value. 

Bitcoins were marked at $7,506.00 each on the bitstamp exchange in Luxembourg, which feeds prices into the CME Group futures contract, down 8.14% from Sunday's close and more than 60% from its all-time peak of $19,187 on Dec. 16. The corresponding declines in other digital coins, including ripple and ethereum, have taken the global cryptocurrency "market cap" to $400 billion - around half of the value it commanded at its mid-December peak.

Lloyds confirmed reports Monday that it would ban credit card purchases in the digital currency market for its 9 million customers, following similar prohibitions from U.S. banks JPMorgan Chase & Co. (JPM) and Citigroup (C) . JPMorgan Chase is a holding in Jim Cramer's Action Alerts Plus.

"Across Lloyds Bank, Bank of Scotland, Halifax and MBNA, we do not accept credit card transactions involving the purchase of cryptocurrencies," a bank spokesperson told Reuters.

Bitcoin prices have fallen more than 45% so far this year, amid a host of factors that have combined take the global value of cryptocurrencies form $800 billion to under $400 billion. 

The most significant pressures, however, appear to be linked to a broader regulatory crackdown and recent moves by Action Alerts Plus holding Facebook Inc. (FB) to ban cryptocurrency-related ads from its platform.

Facebook's decision to remove ads that "promote financial products and services that are frequently associated with misleading or deceptive promotional practices, such as binary options, initial coin offerings and cryptocurrency" accelerated bitcoin's decline this week, as did reports that U.S. Commodity Futures Trading Commission officials served subpoenas to one of the world's biggest digital currency exchanges.

More from Bitcoin

SEC Says Bitcoin and Ether Are Not Securities -- but Prices Stay Bearish?

SEC Says Bitcoin and Ether Are Not Securities -- but Prices Stay Bearish?

CoinShares: US Investors Should Think of Bitcoin as Digital Gold

CoinShares: US Investors Should Think of Bitcoin as Digital Gold

Bitcoin Today: Prices Close to Flat in Low-Volume Trading

Bitcoin Today: Prices Close to Flat in Low-Volume Trading

IBM, Oracle, Microsoft and Others Are Plunging Into 'Blockchain-as-a-Service'

IBM, Oracle, Microsoft and Others Are Plunging Into 'Blockchain-as-a-Service'

Cryptocurrencies Could 'Bring the Internet to a Halt', Central Bank Agency Warns

Cryptocurrencies Could 'Bring the Internet to a Halt', Central Bank Agency Warns