NEW YORK  — Wall Street got its first taste of bitcoin on Monday, with the price of the first-ever futures contract for the digital currency jumping 20 percent.

It’s a step forward for the bitcoin, which has soared this year despite concerns that the surge of investor interest has transformed it from a new-age currency into just the latest speculative bubble.

One prominent securities regulator warned that people were now taking out second mortgages on their homes to buy bitcoin.

The January contract for bitcoin futures closed at $18,545 on the Cboe Futures Exchange. Trading began Sunday and the price rose as high as $18,850, according to data from the Cboe.

The bitcoin futures first day of trading was not entirely smooth. The Cboe’s website crashed several times or slowed down, due to a surge of interest. The exchange halted trading twice on the first day to stem volatility. The exchange operator has rules in place to stop trading after price swings of 10 percent.