Pedestrians look at monitors showing the prices of virtual currencies at the Bithumb exchange office in Seoul, South Korea, Feb. 2, 2018.

Bitcoin is not holding up to its key promises to investors.

First, the cryptocurrency is not acting as a store of value during the U.S. stock market's worst sell-off in years. Bitcoin dropped 15.5 percent Monday to its lowest since mid-November, while the fell 4.1 percent in its worst day in six years.

As U.S. stock index futures dropped Tuesday, pointing to a third day of sharp losses, bitcoin fell below $6,000 to hit its lowest since Nov. 13, according to CoinDesk. Bitcoin recovered slightly in afternoon trading to near $7,270, still down about 28.5 percent for February.

On a year-to-date basis, bitcoin has lost half its value, while the S&P is down 0.92 percent.

Neither is bitcoin holding up as "digital gold." Futures for the precious metal fell just 0.06 percent during Monday's stock market plunge, and are up 2.58 percent for the year so far.