The U.S. Securities and Exchange Commission (SEC) has reportedly asked exchange-traded fund (ETF) issuers to withdraw their 19b-4 filings for XRP, Litecoin (LTC), Solana (SOL), Cardano (ADA), and Dogecoin (DOGE) ETFs.  This comes after the SEC recently approved new generic listing standards for commodity-based ETFs, including cryptocurrency-based ones.