Nora Ali and Brad Smith take a look at how some of the major digital currencies are performing this week. Bitcoin has been trading in the low $8,000 range this week, falling from its highs of $9,000 earlier this month. Jack Dorsey spoke at the Consensus conference in New York on Wednesday, saying he hopes bitcoin will soon become the universal currency of the internet. Cryptocurrency start-up Circle secured another round of funding this week, bringing its valuation to almost $3 billion. It's one of the largest funding rounds for a crypto start-up to date. Circle is looking to create a stable digital coin tied to the U.S. dollar.