The Securities and Exchange Commission will adopt a longer review period for VanEck's proposed bitcoin ETF to ensure it has "sufficient time" to evaluate the proposal, Coindesk reports.As a result, a decision on the VanEck bitcoin ETF will be pushed to at least June.VanEck has filed one of nearly 10 active bitcoin ETF applications; the SEC is currently reviewing three of them.A bitcoin ETF is expected to boost mainstream adoption of the cryptocurrency, as a regulated product would allow retail traders and financial institutions to gain exposure to bitcoin without directly investing in the digital asset.Bitcoin is trading down 1.2% in the past 24 hours, recently trading at $54.4K.In late March, Fidelity Investments said it's hoping to launch its own ETF called Wise Origin Bitcoin Trust.