Bitcoin startup Coinbase is seeking to raise another round of funding, which could add $50 million in new capital before it’s finished. According to sources, however, the company has faced headwinds in the fundraising process that may limit the total amount raised.

Sources tell us Coinbase is raising $50 million of new capital less than a year after its last financing, a $25 million Series B led by Andreessen Horowitz. That’s a pretty big jump in a short period of time, and would once again make Coinbase the best-capitalized Bitcoin startup after recent $30 million funding rounds for BlockChain and BitPay.

(FWIW Re/code, which was apparently chasing this story at the same time we were, reports DFJ is linked to the funding round. Coinbase, btw, declined to comment.)

That said, one source tells us Coinbase started out with an even more ambitious goal during the fundraising process, initially seeking to raise up to $150 million.

So what happened? Our sources say Coinbase has faced headwinds due to regulatory overhang in the U.S., as well as questions about the volatility of Bitcoin as the price of the cryptocurrency has fallen dramatically in recent months.

On the regulatory side, there’s the usual uncertainty about how different governments will seek to handle cryptocurrencies over time. Frankly that hasn’t stopped many investors from pouring money into Coinbase or other Bitcoin-based startups to date.

However, we are hearing rumblings from within the Bitcoin community that Coinbase is being looked at closely by certain state and federal regulators in the U.S.

That might help explain Coinbase’s recent expansion into 13 European countries. While each new country presents new regulatory challenges, being available in more places will help mitigate some of the risk associated with being dependent on customers within any one market.

Meanwhile, Bitcoin volatility could also have been a factor Coinbase’s ability to close its massive funding round, our sources say. The cryptocurrency was trading in the mid-$600s earlier in the summer, and the price has fallen precipitously since then. It had been cut by as much as 50 percent and has traded below $400 for much of the last six weeks.

While most investors who would put money in are still bullish on Bitcoin over the long term, it’s obviously easier to make the case for investment in a startup in the space when the price is rising as opposed to falling.

There is a correlation between the price of Bitcoin and public interest in it. That is, the higher Bitcoin’s price rises, the more attention the average person affords it. Presumably, that interest leads to higher engagement.

A lower price could imply a slower influx of new Bitcoiners, and perhaps a slimmer funnel for the startups battling for domination of this particular market niche.

Regardless of whether Coinbase is able to raise more, with $50 million in fresh capital the company would be well-poised to continue its geographic expansion. Whether it is racing ahead of its market, however, is a separate question.