Guillen expected to sell 215,718 shares for $129 million that day, and that he offloaded 145,289 shares worth $89.6 million on June 14, and 90,111 shares worth $55 million on June 10.
INX, a Gibraltar-based company with most of its operations in the United States, in August launched the first security token IPO for both retail and institutional investors approved by the US Securities and Exchange Commission.
Security tokens are digital currencies backed by a tradable asset such as real estate or equity and are subject to federal regulations. The tokens represent a right to the underlying asset.
The move under the Congressional Review Act, a 1996 law that requires only a simple majority vote in the two chambers of Congress, allows the legislature to reverse recently finalized rules.
Democrats hold slim majorities in the House of Representatives and the Senate.
"The market is going through a 'sell first, ask questions later' phase ... investors think (authorities) want to use the big tech firms to monitor citizens," he said, adding, users may leave such platforms.
The Securities and Exchange Commission (SEC) has meanwhile sought to regulate cryptocurrency investments on the grounds that they qualify as securities transactions.
The central bank has argued that cryptocurrencies, which are unregulated and not legal tender, are risky for the user.
"You are the Secretary of the Treasury, the duties of which require you to be involved in a broad array of matters focused on these sectors," Sonfield wrote.
Securities and Exchange Commission (SEC) officials warned against illegal "manipulative trading activity" .
The Commission will closely review actions taken by regulated entities that may disadvantage investors or otherwise unduly inhibit their ability to trade certain securities.
