Fidelity will allow workers to invest up to 20% of their 401(k) savings directly in bitcoin through the standard investment options menu, making it the first in the industry to offer cryptocurrency investments without a separate brokerage window. This comes as cryptocurrencies move more into the mainstream. However, the U.S. government has warned retirement plans to exercise extreme care with such offerings given the high volatility of cryptocurrencies and their lack of a clear inherent worth. Bitcoin in particular has seen double-digit price plunges in a single day multiple times in the last year alone, whereas the S&P 500 index has only had two such declines in the past 50 years.