Bitcoin BTC treasury firm Twenty One has raised an additional $100 million through convertible senior secured notes, pushing its total capital raised to $685 million as it advances toward a planned merger with Nasdaq-listed Cantor Equity Partners (CEP), a Thursday filing with the U.S. Securities and Exchange Commission shows.

The fresh financing comes from existing investors and sponsors who exercised their option to buy more of the notes, originally granted during the April fundraising round, the regulatory filing said.

The new notes carry a 1% coupon and are due in 2030. The $100 million boost adds to the $385 million initially committed, bringing the total note financing to $485 million. That’s on top of $200 million in private investment in public equity (PIPE) disclosed last month.

CEP is lower by 1.5% in morning U.S. trade as bitcoin slips below $107,000.

Twenty One is the latest example of firms with a crypto treasury strategy, following Michael Saylor’s Startegy (MSTR). The firm is being launched by Brandon Lutnick—the son of U.S. Commerce Secretary and former Cantor Fitzgerald chairman Howard Lutnick—via a a special-purpose acquisition company (SPAC) structure using Cantor Equity Partners. Owners include iFinex—the parent company of Bitfinex—and Tether, the issuer of the $150 billion USDT. The company will be led by Strike CEO Jack Mallers.

The company recently disclosed a $458 million BTC acquisition earlier this month.