Cathie Woods ARK Invest can be thrown at the ring of companies that hope to offer a bitcoin-back exchange traded fund.Woods filed a regulatory filing Monday to launch the ARK 21Shares Bitcoin Exchange Traded Fund. The 21 may be a reference to the 21 million BTCUSD, -0.23%, that will ever be produced from the world's No. Satoshi Nakamoto, creator of the crypto.Woods prospectus is one of many ETF providers and managers looking to offer crypto in an ETF wrapper for the masses.A spokesperson for ARK Invest stated that they could not comment on plans.The CEO of ARK Investment Management and a prominent advocate for disruptive technologies, she has calculated that bitcoin's price, at $34,000, is down approximately 50% since its mid-April peak. If all institutions assign a mid single-digit allocation to the virtual assets, they could put it on their balances, that would make it $500,000ARK Invests actively managed ETFs are recovering from the spring's slump, with a rotation of large-cap tech companies. Barrons reported that her fund had gained 22% on average since May 13th, with the flagship ARK Innovation ARKK (+3.78%) leading the chart. This is more than 30%.Although a bitcoin ETF was once the ultimate goal of the crypto industry's crypto community, it seems increasingly unlikely that one will be realized this year by Gary Gensler (the newly appointed commissioner of the Securities and Exchange Commission).An ETF bitcoin is considered to be more accessible to average investors who want to have direct access to crypto exposures.Woods plans to list a bitcoin ETF could be challenged by Grayscale Bitcoin Trust GBTC (+5.67%), a closed-end bitcoin fund that holds bitcoin. This fund is one of the largest crypto funds. Grayscale trust is also considering converting to an ETF once it has outgrown its current structure. It has yet to apply for this.Ark Invest was a major investor in GBTC recently.