Citigroup Inc. is developing a new mechanism for trading cryptocurrencies such as Bitcoin that would put it at the forefront of Wall Street’s efforts to let clients bet on the largely unregulated market, according to a person with knowledge of the plans.

The bank plans to act as an agent issuing so-called digital asset receipts, or DARs, to enable trading by proxy without direct ownership of the underlying coins, said the person, who asked not to be identified because the information isn’t public. The structure is designed to fall within existing regulatory regimes, giving investors a relatively safe method of trading in crypto.

A representative for the New York-based bank declined to comment on the plans, which were reported earlier Sunday by Business Insider.

The DARs would function similarly to American depositary receipts, or ADRs, which are sometimes used to trade baskets of non-U.S. stocks, according to the person. The cryptocurrencies would be held by a separate custodian.

It’s unclear how U.S. regulators would view DARs. The Securities and Exchange Commission has taken a cautious approach toward virtual currency-linked securities, shooting down several proposals for crypto-themed exchange-traded funds. On Sunday, the SEC temporarily suspended trading in two crypto-linked exchange-traded notes, citing investor confusion regarding the assets.

Concern that the pace of crypto adoption is slowing has weighed on virtual currency markets. After soaring 15-fold in 2017, Bitcoin has lost more than half its value this year. Declines over the weekend reduced the market capitalization of digital assets tracked by CoinMarketCap.com to $196 billion, down about $640 billion from its January peak.

Banks have struggled to offer direct trading in Bitcoin because of the difficulties of acting as custodians of digital assets, which are notoriously susceptible to theft from hackers. A number of firms in the crypto world and on Wall Street have been working on solutions for custody—while others have sought workarounds.

Executives at Citigroup, which earlier this year barred purchases of Bitcoin via its credit cards, see receipts as one of the most direct ways available to mainstream investors to trade Bitcoin.

Citigroup drafted a proposal that identifies three legs to make this type of trading work. Certain firms would buy Bitcoin and deposit it with a custodian of their choice. The bank would then issue receipts to those firms, who could trade the instruments with brokers. That would allow other investors to dabble in Bitcoin by buying and selling the receipts.