Citadel Securities said on Tuesday venture capital firm Sequoia Capital and crypto-focused investment company Paradigm had made a $1.15 billion minority investment in it, giving the market maker founded by billionaire Ken Griffin a valuation of nearly $22 billion.

The funding round was led by Sequoia. Alfred Lin, a partner at Sequoia, will join the board of Citadel Securities, the company said.

The two-decade old company provides trading services to asset managers, banks, broker-dealers and hedge funds. Its institutional business serves over 1,600 clients.

The Chicago-based company has benefited from a surge in trading activity, helped in part by retail investors flocking to popular mobile trading apps since the pandemic began.

GameStop 'Short Squeeze'

Citadel Securities was subjected to a close scrutiny from U.S. lawmakers and regulators, after Robinhood Markets Inc. and several other brokers restricted trading in shares of GameStop Corp in January last year.

The restrictions, which drew the ire of some retail investors, followed a stunning rally that sparked a "short squeeze," leading to billions of dollars in losses for Wall Street hedge funds.

Citadel Securities had made a $2 billion investment in Melvin Capital at the time, after the hedge fund, which had been short on GameStop since 2014, suffered massive losses.

Citadel Securities has denied any involvement in the decision made by the brokers.

The company has a presence in over 50 countries, and plans to use the latest capital to expand globally, according to The Wall Street Journal, which first reported the deal.