Form S-1/A Ark 21Shares Bitcoin

The information in this Preliminary Prospectus is not complete and may be changed. We
may not sell these securities until the registration statement filed with the Securities and Exchange Commission is effective. This Preliminary Prospectus is not an offer to sell these securities and it is not soliciting an offer to buy these
securities in any jurisdiction where the offer or sale is not permitted.

                Shares

ARK 21Shares Bitcoin ETF

The ARK
21Shares Bitcoin ETF (the “Trust”) is an exchange-traded fund that issues common shares of beneficial interest (the “Shares”) that trade on the Cboe BZX Exchange, Inc. (the “Exchange”). The Trust’s investment
objective is to seek to track the performance of bitcoin, as measured by the performance of the CME CF Bitcoin Reference Rate – New York Variant (the “Index”), adjusted for the Trust’s expenses and other liabilities. CF Benchmarks
Ltd. is the administrator for the Index (the “Index Provider”). The Index is designed to reflect the performance of bitcoin in U.S. dollars. In seeking to achieve its investment objective, the Trust will hold bitcoin and will value its
Shares daily based on the Index. 21Shares US LLC (the “Sponsor”) is the sponsor of the Trust, Delaware Trust Company (the “Trustee”) is the trustee of the Trust, and Coinbase Custody Trust Company, LLC (“Coinbase
Custody”) (the “Bitcoin Custodian”) is the bitcoin custodian for the Trust and will hold all of the Trust’s bitcoin on the Trust’s behalf. ARK Investment Management LLC (the “Sub-Adviser”) is the sub-adviser of the
Trust and provides assistance in the marketing of the Shares.

The Trust is an exchange-traded fund. Barring a liquidation or extraordinary
circumstances, the Trust does not intend on purchasing or selling bitcoin, although the Bitcoin Custodian may be directed to transfer or sell bitcoin to pay certain expenses. Instead, when the Trust sells or redeems its Shares, it will do so in “in-kind” transactions in blocks of 5,000 Shares (a “Basket”) that are based on the quantity of bitcoin attributable to each Share of the Trust (net of accrued but unpaid Sponsor Fees (defined
below) and any accrued but unpaid extraordinary expenses or liabilities). Financial firms that are authorized to purchase Shares from or redeem Shares to the Trust (known as “Authorized Participants”) will deliver, or facilitate the
delivery of, bitcoin to the Trust’s account with the Bitcoin Custodian in exchange for Shares, and the Trust, through the Bitcoin Custodian, will deliver bitcoin to such Authorized Participants when they redeem Shares. Authorized Participants
may then offer Shares to the public at prices that depend on various factors, including the supply and demand for Shares, the value of the Trust’s assets, and market conditions at the time of a transaction. Shareholders who buy or sell Shares
during the day from their broker on the secondary market may do so at a premium or discount relative to the net asset value of the Shares of the Trust.

Except when aggregated in Baskets, Shares are not redeemable securities. Baskets are only redeemable by Authorized Participants.

CME CF Bitcoin Reference Rate – New York Variant for the Bitcoin – U.S. Dollar trading pair (the “Index”), produced by
CF Benchmarks Ltd., on [            ], 2023 was $[            ].

On [            ], 2023, the Seed Capital Investor[, an affiliate of the Sponsor,]
subject to conditions, purchased the Seed Creation Baskets, comprising [            ] Shares at a per-Share price of
$[            ], as described in “Seed Capital Investor.” Total proceeds to the Trust from the sale of the Seed Creation Baskets were
$[            ]. Delivery of the Seed Creation Baskets was made on [            ], 2023. The Seed Capital Investor will act as a
statutory underwriter in connection with this purchase.

The price of the Seed Creation Baskets was determined as described above and such
Shares could be sold at different prices if sold by the Seed Capital Investor at different times.

Shareholders who decide to buy or sell
Shares of the Trust will place their trade orders through their brokers and will incur customary brokerage commissions and charges. Prior to this offering, there has been no public market for the Shares. The Shares are expected to be listed for
trading, subject to notice of issuance, on the Exchange under the ticker symbol “ARKB.”

The offering of an indeterminate amount
of the Trust’s Shares is registered with the Securities and Exchange Commission (the “SEC”) in accordance with the Securities Act of 1933, as amended (the “1933 Act”). The offering is intended to be a continuous offering and
is not expected to terminate until three years from the date of the original offering, unless extended as permitted by applicable rules under the 1933 Act. The Trust is not an investment company registered under the Investment Company Act of 1940,
as amended (the “1940 Act”), and is not subject to regulation under the 1940 Act. Investors in the Trust will not, therefore, receive the regulatory protections afforded by investment companies registered under the 1940 Act. The Sponsor is
not an “Investment Adviser” (as defined in Section 202(a)(11) of the Investment Advisers Act of 1940, as amended (the “Advisers Act”)), the Sponsor’s provision of services to the Trust will not be governed by the
Advisers Act, and the Sponsor is not subject to a fiduciary standard of care. The Trust is not a commodity pool for purposes of the Commodity Exchange Act of 1936, as amended (the “CEA”), and the Sponsor is not subject to regulation by the
Commodity Futures Trading Commission (the “CFTC”) as a commodity pool operator or a commodity trading advisor. Shareholders in the Trust will not benefit from the protections afforded to investors in bitcoin futures contracts on regulated
futures markets. The Trust’s Shares are neither interests in nor obligations of the Sponsor, the Sub-Adviser or the Trustee.

AN INVESTMENT
IN THE TRUST INVOLVES SIGNIFICANT RISKS AND MAY NOT BE SUITABLE FOR SHAREHOLDERS WHO ARE NOT IN A POSITION TO ACCEPT MORE RISK THAN MAY BE INVOLVED WITH EXCHANGE-TRADED PRODUCTS THAT DO NOT HOLD BITCOIN. THE SHARES ARE SPECULATIVE SECURITIES. THEIR
PURCHASE INVOLVES A HIGH DEGREE OF RISK AND YOU COULD LOSE YOUR ENTIRE INVESTMENT. YOU SHOULD CONSIDER ALL RISK FACTORS BEFORE INVESTING IN THE TRUST. PLEASE REFER TO “RISK FACTORS” BEGINNING ON PAGE
14.

NEITHER THE SEC NOR ANY STATE SECURITIES COMMISSION HAS APPROVED OR DISAPPROVED OF THE SECURITIES OFFERED IN THIS
PROSPECTUS, OR DETERMINED IF THIS PROSPECTUS IS TRUTHFUL OR COMPLETE. ANY REPRESENTATION TO THE CONTRARY IS A CRIMINAL OFFENSE.

THE
TRUST IS AN “EMERGING GROWTH COMPANY” AS THAT TERM IS USED IN THE JUMPSTART OUR BUSINESS STARTUPS ACT (THE “JOBS ACT”) AND, AS SUCH, MAY ELECT TO COMPLY WITH CERTAIN REDUCED REPORTING REQUIREMENTS.

The date of this Prospectus is [●], 2023