BlackRock files for downside-protected bitcoin ETF, following Calamos

BlackRock filed Monday to launch the iShares Bitcoin Managed Protect ETF, a fund that would give investors bitcoin exposure while seeking to limit losses when the price falls.

The filing, reported by CoinDesk, does not disclose how much downside protection the fund would offer or how much of bitcoin's upside holders could keep. It says the fund would seek "upside exposure to the iShares Bitcoin Trust ETF and/or similar bitcoin exposure up to an approximate limit, while seeking to provide a level of downside protection."

Calamos Investments launched its first three protected bitcoin ETFs in early 2025, offering either full downside protection or losses limited to 10% or 20% over a set period. The firm puts roughly 90% of those funds' assets into U.S. Treasuries and uses the rest to buy bitcoin-linked options, which lets a holder capture gains up to a cap while bounding losses over a defined window.

Calamos's Bitcoin Structured Alt Protection ETF – October (CBOO) fell just 1% from the start of its one-year protection period in October 2025, according to a Calamos spokesperson. Bitcoin, in contrast, tumbled as much as 52% from its record high of roughly $126,000 during the past year's selloff.

The proposed fund would build on the iShares Bitcoin Trust (IBIT), which manages more than $65 billion and is the largest of the U.S. spot bitcoin ETFs introduced in 2024, according to CoinDesk.

In June BlackRock launched the Bitcoin Premium Income Fund (BITA), which holds bitcoin and IBIT shares while selling call options on roughly 25% to 35% of its portfolio to generate monthly income. That fund sells upside for income; a protection fund would buy a floor and pay for it with a cap.

The filing leaves the exact loss limit and the price of that cap for a later amendment. A full-protection version and a 10% or 20% loss limit are different products with different option budgets, and Calamos already prices that choice across its lineup.