Bitcoin seems unstoppable, topping $1,700 for the first time on Tuesday.

The cryptocurrency is up 5.71% at $1,758.45 a coin, as trade grinds higher for the 16th time in 18 sessions. It has gained nearly 50% during its run.

Tuesday's gain comes without any obvious catalyst as traders await the US Securities and Exchange Commission's ruling on whether it will reverse its decision to reject the Winklevoss twins' exchange-traded fund.

The SEC rejected two bitcoin ETFs back in March, saying it "is disapproving this proposed rule change because it does not find the proposal to be consistent with Section 6(b)(5) of the Exchange Act, which requires, among other things, that the rules of a national securities exchange be designed to prevent fraudulent and manipulative acts and practices and to protect investors and the public interest."

Bitcoin recently has shrugged off China restricting trade, the SEC's rejecting of the two bitcoin ETFs, and threats from developers to create a "hard fork" that would split the cryptocurrency in two.

But there has also been some good news for bitcoin, which has posted an 85% gain this year.

At the beginning of April, Japan's financial regulators said bitcoin would be considered a legal payment method in the country, and days later Russia said it would consider bitcoin and other cryptocurrencies in 2018.

Aside from 2014, bitcoin has been the top-performing currency every year since 2010.