Bitcoin prices stumbled towards the key $300-level on Sunday, as bearish chart signals and concerns about possible regulation of the virtual currency weighed. Bitcoin (BTC/USD) lost $69.69, or 18.44%, on Slovenia-based BitStamp to trade at $308.21 during U.S. morning hours. BitStamp prices fell to a session low of $301.00 earlier. The price of a bitcoin on Bulgaria-based BTC-e dropped $63.31, or 17.23%, to trade at $304.10, while prices on Singapore-based itBit slumped $17.69, or 5.4%, to trade at $309.92. According to the CoinDesk Bitcoin Price Index, which averages prices from the major exchanges, prices of the crypto-currency sank 5.19% to trade at $308.60. Market players remain concerned about possible regulation of the virtual currency among other adverse events in the industry. Meanwhile, euro-denominated Bitcoin prices (BTC/EUR) plunged €11.89, or 4.57%, to trade at €248.30 on U.S.-based Kraken Exchange. Elsewhere, yuan-denominated Bitcoin prices retreated CNY397.65, or 17.24%, to trade at CNY1,908.75 yuan on Beijing-based OKCoin, while prices on Shanghai-based BTC China declined CNY114.60, or 5.63%, to trade at CNY1,921.72. Bitcoin is digital cash and is not backed by a government or central bank to regulate or issue it. It can be used to purchase goods and services from stores and online retailers.