What happened

Shares of Overstock.com (BYON -5.05%) gained 35.7% in December 2017, according to data from S&P Global Market Intelligence. By and large, the online retailer tapped into surging cryptocurrency markets.

So what

Overstock is a well-known early adopter of blockchain technologies. The company has been accepting retail-level payments in bitcoin since 2014, and Overstock's own research and development of blockchain-based technologies has hatched a new platform for trading of stocks and other financial instruments.

So it's not surprising to see Overstock shares surge in a month where bitcoin prices peaked just below $20,000 per coin, up from $1,000 at the end of November. When the bitcoin, Ethereum, and Litecoin mania took a step back in the middle of the month, so did Overstock's share prices.

Businessman studies a wall-sized poster of a simple blockchain illustration, titled BLOCKCHAIN in capital letters.

Image source: Getty Images.

Now what

The tight bond between bitcoin prices and Overstock's shares is real. In December, CEO Patrick Byrne announced a low-cost stock trading platform built on blockchain transactions, right after telling investors that he might want to sell Overstock's e-commerce operations to pour that windfall into more cryptocurrency and blockchain business ideas.

So investors are largely forgetting about Overstock's online retail operations to focus on the company's crypto-tech future. If you want to bet on the success of bitcoin and friends without actually owning any coins, Overstock could be a good way to get started. Or, if you're a cryptocurrency skeptic, you might want to stay far away from this stock until further notice.