Senator Elizabeth Warren voiced concerns about Fidelity Investments' plan to include bitcoin in customers' 401(k) accounts, calling it "a risky and speculative gamble."

In a letter dated 4 May to Fidelity CEO Abigail Johnson, Warren and co-author, senator Tina Smith,  expressed concern about potential conflicts of interest — Fidelity started mining bitcoin in 2017 — and questioned why the company ignored a Labor Department statement from March that laid out "serious concerns" about exposing 401(k) accounts to cryptocurrencies, citing "the significant risks of fraud, theft and loss."