BlackRock has filed for a new bitcoin ETF designed to shield investors from downside losses, following the collapse of rival fund Calamos' protected bitcoin products by 50%. The filing does not specify the extent of downside protection or the cap on upside participation. The move mirrors Calamos' strategy, launched in early 2025, which allocates roughly 90% of assets to U.S. Treasuries and uses the remainder for bitcoin-linked options to limit losses over defined periods while capturing capped gains. Calamos' head of ETFs Matt Kaufman noted in May that the protected funds attracted $10 million to $15 million amid outflows from spot bitcoin ETFs. BlackRock recently expanded its non-traditional crypto offerings with the June launch of the Bitcoin Premium Income Fund (BITA), which holds bitcoin and IBIT shares while selling call options on 25% to 35% of the portfolio to generate monthly income.