The bitcoin price has been in the doldrums in the last week, closing out a month of persistent losses. It's now trading at the lowest levels of the year.

Bitcoin opened the week at $330.67 and closed at $316.80, according to the CoinDesk Bitcoin Price Index. That represented a loss of $13.87 in the bitcoin price over the last seven days, or 4.2%.

Over the week, the price hit a high of $335.88 on the 23rd December, only to fall to a low of $312.40 four days later. That was a drop of some $23.

The bitcoin price has not been kind to bulls this month. While it was trading in the high-$300s – even breaking the $400 mark at one point – in November, the start of December saw a period of sustained downward pressure on BTC/USD.

Trading volumes offer little optimism. Volumes have fallen sharply across the board this week, with the total amount of bitcoins changing hands down by 24% compared to the previous week, according to data from Bitcoinity. The Christmas holidays this week surely deepened the decline.

Big Chinese exchanges OKCoin and BTC China showed drops of 18% and 17% respectively. Exchanges elsewhere showed far steeper plunges, with Bitstamp showing a decrease in trading volume of 56% and Bitfinex showing a 54% drop.

One market observer attributed December's plummeting price to widespread tax-reduction measures. In December, investors in the US securities markets often offload stocks or other assets that have performed poorly at a loss in order to avoid paying short-term capital gains taxes. The practice influences the markets so greatly that trading strategies have been devised around these fluctuations.

It's tax-loss selling that could be driving the bitcoin price down in December, says Harry Yeh, managing partner at digital currency fund Binary Financial. Punters who speculated on bitcoin and lost have the option of cutting their losses by selling in December, before the new tax season starts.

With bitcoin now trading in the low $300s, Yeh said it has bottomed out and that is poised for a rebound in the coming year.

One catalyst that could give a bitcoin rebound impetus is the rise of derivatives, Yeh said.

As futures contracts become more widespread in the cryptocurrency world, payment processors, miners and speculators gain the ability to hedge their bitcoin holdings. This should make them more comfortable holding larger quantities of bitcoin, according to Yeh.

The Nasdaq's Martin Tillier broadly agrees. In his outlook for bitcoin in 2015, he also pointed to holding power as the main driver for a rising bitcoin price.

For Tillier, the big merchants who have announced that they will accept bitcoin payments this year have been putting selling pressure on the price because they don't hold on to assets in bitcoin. Instead, they immediately convert any bitcoin holdings to fiat currency.

In the coming year, some of these merchants will start to hold bitcoin instead of cashing out instantly. As merchants begin to hold bitcoin and transact with one another in the digital currency, demand for bitcoin will creep up again, boosting the price, Tillier argued.

Looking at the larger macro factors, there's always the possibility that a fiat currency will lose its value so quickly that bitcoin begins to look like a safe haven.

The Russian ruble for example has lost about a third of its value against the US dollar this year. Trading volumes in the BTC/Ruble currency pair have enjoyed growing volumes this year on both the BTC-e exchange and the Local Bitcoins peer-to-peer marketplace, according to data from Bitcoin Charts.

As bitcoin tests new lows at the end of 2014, it seems the bears have won this year. Bitcoin bulls must hope that the new year offers fresh hope for a lift in prices.

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