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.

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Recently, a number of high profile online merchants started accepting bitcoin payments including Dell, Overstock (OSTK) andExpedia (EXPE). 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.

"The view is that some early adopters are making moves at the moment - and you can see that in all of the publicly available exchange trade data," he added.

Bitcoin was the center of a media frenzy last year after it rose 8,000 percent from January to early December. Prices halved soon after amid regulatory concerns.

The cryptocurrency has since fallen out of the spotlight, save for a brief flash crash in August, when prices fell 12 percent during one day, due to concerns about state-specific regulation in in New York. Prices are down 73 percent their all-time high of $1,147 hit on December 4, 2013.

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Interest to remain

Price declines over the weekend are unlikely to deter investors, said David Moskowitz, director at Singapore-based bitcoin trading firm Coin Republic.

"I think the price is really irrelevant to the technology. Obviously it hurts investors when the price goes down but most people who are buyers are in it as long term investors and can withstand the short term gyrations," he said.

"Adoption has continued to increase there has been a tremendous amount of good news over the past year especially with more well-known merchants taking it on," he said.

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Sharp price swings could be positive for bitcoin ANX's Madden said: "It creates headlines and as a result people start to read about it and [attracting] a lot of interest."

Last month venture capitalist Tim Draper forecast that bitcoin prices would rise to $10,000 over the next three years. Draper has a vested interest; he owns 0.25 percent of the market after winning a giant government bitcoin auction in July.

Bitcoin was trading at $306.43 in Asian market hours on Monday, according to CoinDesk.