Bitcoin lost nearly a fifth of its value over the weekend, raising concerns that investors are losing faith in the cryptocurrency. Prices fell to a year-to-date low of $290.83 on Sunday, down over 18 percent from early Saturday, according to bitcoin news blog CoinDesk. Analysts are citing a number of factors for the decline: bearish chart signals; ongoing regulatory concerns; large sell orders by some early adopters; and a shift in the supply/demand balance. "The rumors are that for some time now there's been a lot of success in 'off ramp' – but the onboarding process hasn't caught up as quickly," Hugh Madden, co-founder of Hong Kong-based bitcoin exchange ANX, told CNBC, referring to the ability of holders to spend bitcoins. Read MoreBitcoin: CNBC Explains

George Frey | Getty Images

Recently, a number of high profile online merchants started accepting bitcoin payments including Dell, Overstock and Expedia. Online payment processing giant PayPal plans to allow bitcoin payments through integration with bitcoin payment processing companies Bitpay, Coinbase and GoCoin, three of the largest bitcoin payment processing companies. "It's actually a lot harder to get bitcoins than it is to spend them and there have been some suggestions that that's caused a supply/demand imbalance… PayPal integration would also improve that onboarding process," Madden said. Early adopters Some of the heavier declines may have been triggered by larger sell orders by a small number of bitcoin investors, Madden said.